# Seminars and Colloquia at ESO Santiago

## December 2019

19/12/19 (Thursday)
16:00, Licancabur meeting room | ESO Santiago
JAO Colloquium
Talk — ASPECS: The ALMA Spectroscopic Survey in the Hubble Ultra-Deep Field
Roberto Decarli (INAF-OAS Bologna)

## Abstract

We present the results of the ALMA large program ASPECS. In the deepest continuum imaging obtained for an extragalactic deep field (rms: 9 uJy at 240 GHz) we detect dust emission from 35 individual galaxies that are found to span a wide range in stellar mass, star formation rate, HST morphology, reddening, and nuclear activity, both on and off the galaxy main sequence. Some of the galaxies are faint the optical and would be considered â€˜HST darkâ€™ in fields that do not reach the depth of the UDF. Number counts indicate a clear flattening of the counts towards the faintest flux levels, suggesting that it will be challenging to significantly push the number of detected sources in the UDF with future ALMA observations. The IRX-beta relationship derived from ASPECS lies approximately half-way between a Calzetti-like relation and an SMC relation and can be used to improve the constraints on the cosmic star formation rate density. Most of the dust-detected galaxies are also detected in molecular gas emission (typically CO) through frequency scans in both the 3mm and 1mm bands. In many cases, multiple CO lines are detected which are used to constrain the excitation of the molecular gas component. Stacking in both the continuum and line (capitalizing on >1000 spectroscopic redshifts from MUSE) is employed to push our detection limits to unprecedented depths. The nature of the observations (full spectral scans) provides a census of dust and molecular gas in the cosmic volume defined by the UDF. The resulting cosmic molecular gas density as a function of redshift shows an order of magnitude decrease from z=2 to z=0. This is markably different from independent measurements of the atomic gas phase that shows a rather flat redshift dependence. This difference can be used to put new constraints on the gas accretion process that is needed to explain the build-up of stellar mass in galaxies through cosmic history.

16/12/19 (Monday)
12:00, Library (ESO, Vitacura) | ESO Santiago
TMT (30 minutes talk)
Talk — Probing the Inner AU of Disks with Infrared Polarinterferometry
Benjamin Setterholm (University of Michigan, USA)

## Abstract

Protoplatetary disks provide a direct look at the processes leading to planetary systems, such as our own. While large solitary telescopes and millimeter arrays have revealed grand disk features and hints of giant planet formation, these facilities are unable to resolve the sub-au structures pertinent to terrestrial planet formation.  Recent investigations using long-baseline optical interferometers - capable of probing these spatial scales - have failed to find an expected dust-evaporation front in the inner-au in several protoplanetary disk systems, unveiling instead strong near-infrared emission much closer to the central star than previously imagined.  To discriminate between possible origins of this mysterious emission, which may have important implications in disk evolution the formation of terrestrial planets, we augmented the 6 telescope MIRC-X beam-combiner at the CHARA array with polarimetric optics to search for scattered light signatures in these systems.  Herein, I present the current progress in the development of this new instrument mode.

12/12/19 (Thursday)
12:00, Library (ESO, Vitacura) | ESO Santiago
Talk — Disentangling Cataclysmic Variables in Gaia's HR-Diagram
Javier Abril (ESO)

## Abstract

Cataclysmic Variables (CVs) are interacting binaries consisting of at least three components that control their colour and magnitude. Using Gaia we here investigate the influence of the physical properties of these binaries on their position in the Hertzsprung-Russell diagram. The CVs are on average located between the main sequence and the white dwarf regime, the maximum density being at Gbp-G_rep ~ 0.56 and Gabs ~ 10.15. We find a trend of the orbital period with colour and absolute brightness: with decreasing period, the CVs become bluer and fainter. We also identify the location of the various CV sub-types in the HR-diagram and discuss the possible location of detached CVs, going through the orbital period gap.

11/12/19 (Wednesday)
16:00, Licancabur meeting room | ESO Santiago
JAO Colloquium
Talk — Dissecting an ARC: DO-(e)ing it
Raúl Aliaga-Díaz, Sebastián Cornejo, Pedro Daire, Faviola Molina (Data Observatory)

## Abstract

The Data Observatory (DO) is an open innovation science-driven instrument, a neutral broker at the heart of industry, academy and government collaboration for Science, Technology, Knowledge and Innovation. The DO will facilitate untethered access to public data and specially curated datasets for research challenges. One of our scopes is to enable collaboration with a large and active data science community, boosting the productivity of their data in a broad sense that includes research publications and can lead to talent, technology and infrastructure development.
Astronomy was selected as the first domain of engagement for the DO and it started successfully in 2019. The first milestone in the 5-year roadmap is the implementation of the computing infrastructure of a Chilean ALMA Regional Center (ARC-i). We are using cloud-based technologies like containerization and serverless computing in the deployment of an ARC-i based on non-reserved cloud-based infrastructure. Our plan is focused on enabling this implementation and developing Data Science capabilities for transferring it across domains.

15:30, Library (ESO, Vitacura) | ESO Santiago
ESO Colloquium
Talk — SW Sextantis stars - A l ink between Polars and Intermediate Polars?
Linda Schmidtobreick (ESO, Chile)

## Abstract

Polars are cataclysmic variables whose white dwarfs inhibit strong magnetic fields (>5MG). These systems are mainly found at short orbital periods. Intermediate polars, whose white dwarfs have lower magnetic fields (0.5-5MG), are more dominant at longer orbital periods. Since the secular evolution of CVs goes from long orbital periods to short orbital periods, the question arises whether the magnetic field of a white dwarf can increase during the binary evolution. Theories allow such a field enhancement in case of strong accretion. A phase of high mass transfer is the SW-Sex stage, which is dominantly observed at periods between 3 and 4 hours - about the border region between the intermediate polars and the polars. In this talk, I will review some observational evidence as well as theoretical possibilities which can explain the period distribution of polars, intermediate polars and SW Sex stars.

06/12/19 (Friday)
12:00, Library (ESO, Vitacura) | ESO Santiago
TMT (30 minutes talk)
Talk — Dance of death in the planetary graveyard
Boris Gaensicke (U. Warwick, UK)

## Abstract

Many of the known planets - in the solar system Mars and beyond - will survive the post main-sequence evolution of their host stars into white dwarfs. Later interactions scatter asteroids, moons, and possibly entire planets deep into the gravitational potential of the white dwarf, where they are disrupted, and eventually accreted. These systems can inform us on the conditions and the efficiency of planet formation, and on the architectures of outer planetary systems inaccessible to direct detections.  I will showcase the rich observational evidence for evolved planetary systems, and announce the discovery of the first giant planet in a close orbit around a white dwarf (made with X-Shooter).

02/12/19 (Monday)
15:30, Library (ESO, Vitacura) | ESO Santiago
TMT (30 minutes talk)
Talk — A new class of Fe-rich tidal disruption events
Thomas Wevers (Univ. of Cambridge, UK)

## Abstract

Tidal disruption events occur when a star passes so close to a supermassive black hole in the centre of a galaxy that the gravitational tidal forces overcome the star's self-gravity, and it gets ripped apart into streams of gas. Part of this material is gravitationally bound, and will be accreted; this process is visible as a luminous panchromatic flare of radiation. This material is thought to form an accretion disk when the streams self-intersect and shock. However, some theoretical considerations suggest that disk formation may be signifcantly delayed due to the inability of the debris streams to lose angular momentum.
I will present UV, optical and X-ray follow-up observations of a new, peculiar X-ray bright tidal disruption event, where we have found direct evidence for the rapid formation of an accretion disk. We infer this from the emergence of narrow optical Fe ii emission lines in the optical spectra during a plateau phase in the lightcurve.
I will discuss the properties of this new spectroscopic class of TDEs, as well as the implications for disk formation in TDEs.

12:00, Library (ESO, Vitacura) | ESO Santiago
TMT (30 minutes talk)
Talk — A MUSE perspective on galactic "missing" baryons at z~3
Gabriele Pezzulli (ETH Zurich)

## Abstract

Galaxy formation models rely on mechanisms to keep the majority of
baryons outside of the main body of galaxies. Different scenarios,
however, make different predictions about where these "galactic missing
baryons" should be found: relatively close-by in the so-called
circumgalactic medium (CGM), or very far away in the diffuse
intergalactic medium (IGM). Observational determinations of the CGM
baryon fraction within galaxy haloes are therefore of great importance
to constrain galaxy formation and especially feedback models.
In this talk I will present a MUSE perspective on this fascinating
problem. In particular, as I will show, MUSE observations Giant Ly-alpha
nebulae around z~3 quasars, combined with a multi-phase model of the
CGM, indicate that massive haloes at this redshift retain a substantial
fraction of their baryons within their virial radius, possibly favouring
models of cooling prevention, or baryonic circulation, over those
requiring very strong ejective feedback. I will put emphasis on the most
important current uncertainties and how these can be overcome by more
observations and theoretical models in the future.

## November 2019

29/11/19 (Friday)
12:00, Library (ESO, Vitacura) | ESO Santiago
TMT (30 minutes talk)
Talk — Papa Beaver’s Storytime
Fred Vogt (ESO, Chile)

## Abstract

"Père Castor ne laisse jamais passer une occasion de raconter une histoire à ses trois enfants, Câline, Grignote et Benjamin. Il les laisse ensuite en tirer leurs propres conclusions.”

11:30, Licancabur meeting room | ESO Santiago
JAO Colloquium
Talk — The [C/N] abundance ratio traced by [CII] 158 μm & [NII] 205 μm observations towards the Arched-Filaments at the Galactic Center
Dr. Pablo García (Researcher and Project Assistant, National Astronomy Observatory of China CASSACA)

## Abstract

The Arches Cluster − Arched-Filaments (AFs) physical system offers a unique opportunity to study the close relationship between Photon-Dominated Regions (PDRs) and H II regions, and their relative contributions the total observed [CII] emission, in the harsh environment of the Galactic Center. In that context, we have investigated the [CII] vs. [NII] scatter relationship in the AFs region in order to assess the [CII] emission contribution from the H II region and PDR components, traced by [NII] observations, in the high metallicity environment of the GC. Our results show that the [CII] vs. [NII] scatter relationship in the AFs can be explained by variations of the [C/N] elemental abundance ratio in the range 0.84 < [C/N] < 1.41, for metallicities Z, hydrogen volume densities n(H), and ionization parameters U consistent with the gas physical conditions in the GC. The fraction of the total observed [CII] emission arising from within PDRs varies between 0 to 0.75 in the AFs. From the emission originated within the H II region component, we found an average carbon-to-nitrogen elemental abundance ratio [C/N] = 1.13 +/- 0.09 and a lower limit for the nitrogen elemental abundance [N/H] = 6.21 x 10^-4, the latter a factor of ~ 2 higher than previous estimates for the same AFs region. We suggest that secondary production of nitrogen from low to intermediate mass stars in the Galactic Bulge is a plausible mechanism to explain the large abundance differences between the GC and the Galactic Disk.

28/11/19 (Thursday)
12:00, Library (ESO, Vitacura) | ESO Santiago
ESO Thirty Minute Talks
Talk — Exploring the link between Quasar outflows and Hot Dust emission
Matthew Temple (Cambridge University, UK)

## Abstract

It has been known for several decades that quasars (and other AGN) show an excess of emission around 1um, usually attributed to emission from T~1200K dust at the sublimation radius which is being heated by the quasar UV continuum. There exists a large range of variation in the infrared SEDs of quasars at any given redshift, showing that there is a wide range of hot dust properties within the quasar population. However, it is not yet clear how these hot dust properties relate to other AGN properties such as the black hole mass, luminosity and accretion rate.
In recent years there has been a huge increase in the number of spectroscopically confirmed quasars due to large surveys like the SDSS, which now has spectra of hundreds of thousands of quasars spanning almost two orders of magnitude in luminosity and Eddington fraction. Using this data set, and also photometric data from wide-field infrared surveys, we investigate how the infrared properties of quasar SEDs are connected with these parameters and also with the properties of the high-ionisation CIV broad emission line. CIV exhibits a large range of kinematic morphologies, including asymmetric emission which is blueshifted by several thousand km/s in some objects. These emission line shifts are believed to indicate the presence of strong nuclear outflows, most likely being driven by a wind off the accretion disc.
We find a link between the strength of the hot dust emission and the speed of outflows in quasars, and use our results to place constraints on models of AGN geometry.

27/11/19 (Wednesday)
15:30, Urania room (ESO, Santiago) | ESO Santiago
ESO Colloquium
Talk — Probing the cold neutral medium at high redshift with quasar absorption line spectroscopy.
Serj Balashev (Ioffe Institute, Saint Petersburg, Russia)

## Abstract

I will summarize our recent results of the studies of the cold phase of the diffuse interstellar medium (ISM) of high-z galaxies. The cold phase of ISM can be probed using molecular hydrogen (H2) bearing Damped Lyman Alpha (DLA) system in quasar spectra. Using SDSS, now, we can efficiently preselect such systems, and then analyze in detail with follow-up observations using UVES and X-shooter at the VLT. The high-resolution data allow us to determine the chemical composition and physical conditions in the diffuse ISM of high redshift galaxies. I will show the results of several recent observations of H2-bearing DLAs, including extremely high H2 column density low metallicity DLAs, with log(N(H2), cm^-2) ~ 21.3. Although high H2 content, we did not detect CO absorption lines, putting a strict lower limit for X_CO conversion factor at low metallicity medium. These clouds seem to be the analogs of star-forming molecular clouds, seen in the local galaxies.

26/11/19 (Tuesday)
12:00, Library (ESO, Vitacura) | ESO Santiago
TMT (30 minutes talk)
Talk — RAMSES, a tool to compute an instrumental wavelength solution
Marcelo Tala (Landessternwarte, Zentrum für Astronomie der Universität Heidelberg)

## Abstract

Current state-of-the-art echelle spectrographs derive the wavelength

solution - the function that maps from pixel to wavelength space - in a

purely empirical way, by  fitting polynomials to a sparse calibration

lines spectrum. One way to ensure that the engineering data propagates

from instrument building to operations is to use all design and

engineering information in a physical model-based description of the

instrument and use this to compute the wavelength solution. With the aim

of fitting an echelle spectrograph model to real spectroscopic data to

understand the instrument behavior, I developed RAMSES, a ray tracing

software that calculates the optical path of individual rays through an

echelle spectrograph from the slit to the detector. By including the

effects of the environment on the physical properties of the optical

elements that compose the spectrograph, I am able to reproduce some of

the trends observed in the time series of the spectral line positions of

the CARMENES calibration data and constraint the nature of the observed

RV systematics.

21/11/19 (Thursday)
12:00, Urania room (ESO, Santiago) | ESO Santiago
TMT (30 minutes talk)
Talk — Water vapor in galaxies near and far
Chentao Yang (ESO/ALMA)

## Abstract

Submillimeter H2O lines are unique diagnostic tools of the physical conditions of the interstellar medium and properties of the radiation field in the warm dense gaseous regions of infrared-luminous galaxies. H2O is the second strongest molecular emitter in the submillimeter band after the CO lines in infrared-bright galaxies. In nearby galaxies, Herschel Space Telescope has made significant progress in understanding the H2O emission/absorption. While the H2O lines are readily accessible at high redshift when they are shifted into atmospheric millimeter windows, especially in the strongly lensed galaxies with current ground-based (sub)mm telescopes. This talk gives a brief review of the recent progress of the observations of the emission and absorption lines of H2O across cosmic time based on recent NOEMA and ALMA results and discusses the physical properties of the interstellar medium and the radiation fields inferred from the excitation of the H2O lines. Besides H2O, the talk also presents recent detections of H2O+ lines in a few high-redshift sources, which enables us to study the ionization state of the interstellar medium in the early universe and the formation of H2O through ionic reactions.

19/11/19 (Tuesday)
14:30, Urania room (ESO, Santiago) | ESO Santiago
ESO Colloquium
Talk — Prospecting for quadruply lensed quasars in the past decade and the next
Prof. (em) Paul Schechter (MIT)

## Abstract

Quadruply lensed quasars ("quads") are used to study several important astronomical problems, one of which, the abundance of LIGO-mass primordial black holes, we discuss at some length.  But quads are
rare, with only one out of every 3000 quasars lensed into a quad.  The alternative schemes used to identify them all have serious shortcomings of either an astrophysical or observational nature.  The ground- and space-based surveys of the past decade have nonetheless yielded dozens of new quads.  The surveys of the next decade will produce many hundreds.  We discuss various different search techniques, some of which have until now proven productive and others of which are soon likely to be so.

12:00, Library (ESO, Vitacura) | ESO Santiago
TMT (30 minutes talk)
Talk — How does the galaxy cluster environment affect molecular gas and star formation? - The ALMA Fornax Cluster Survey
Nikki Zabel (Cardiff, UK)

## Abstract

When many galaxies crowd together in a small space, the environment gets harsher and more stressful for them. As a result, they wear out more quickly and retire younger than their peers in less populated areas: their star formation is quenched rapidly. This is why in galaxy clusters we find a large fraction of early-type galaxies compared to late-type spirals, which are much more common in the field.

It has been known for a while that the responsible mechanisms for this early quenching, such as ram pressure stripping, galaxy-galaxy interactions, and starvation, play a significant role in removing the atomic gas from galaxies. If they are able to also directly affect the much more tightly bound and centrally located molecular gas, is less obvious. Since this gas is the direct fuel for star formation, this would have important implications for the evolution of cluster galaxies, and, with many galaxies residing in clusters and groups, galaxy evolution in the universe. With the ALMA Fornax Cluster Survey we study the molecular gas in Fornax cluster galaxies to find out whether the molecular gas in cluster galaxies can be removed directly through these processes, and how this affects their star formation.

14/11/19 (Thursday)
16:00, Licancabur meeting room | ESO Santiago
JAO Colloquium
Talk — Exploring the effects of stellar multiplicity on planet formation
Nicolás Cuello (FONDECYT Postdoctoral Fellow, Institute of Astrophysics (PUC))

## Abstract

Three facts: 1) stellar multiplicity is high during early stellar evolution, 2) planet formation occurs early on, and 3) planets are detected in multiple stellar systems. Three consequences: 1) planet formation does not occur in isolation, 2) planet formation is resilient, and 3) the environment of stellar formation affects the final planetary architecture. In this talk we explore circumbinary discs dynamics and also discs affected by stellar flybys, mainly through 3D SPH hydrodynamical simulations. The goal is to better understand the initial conditions for planet formation in multiple systems. Based on these findings, we build a catalogue of observational signatures of such discs using MCFOST. To conclude, we connect these synthetic observations to recent multi-wavelength observations of discs exhibiting mysterious asymmetries (e.g. AS 205, UX Tau, FU Ori). Our conclusion: stellar multiplicity deeply affects planet formation.

12:00, Urania room (ESO, Santiago) | ESO Santiago
ESO Colloquium
Talk — The high-redshift universe in Lyman-alpha emission
Lutz Wisotzki (Leibniz-Institut für Astrophysik Potsdam (AIP))

## Abstract

Lyman-alpha radiation is a natural signature of star-forming galaxies and has been used since long to identify high-redshift objects. I present observations with the MUSE instrument at the ESO-VLT that have revealed more than 1000 Lyman-alpha emitters, some of them extremely faint. Moreover, we find ubiquitous extended Ly-alpha emitting envelopes around individual normal (non-AGN) galaxies at redshifts z > 3. These Ly-alpha haloes indicate huge reservoirs of cold gas in the circumgalactic medium. At the sensitivity level reached by MUSE, a large fraction of the field of view is actually covered with Lya emission from redshifts 3 < z < 6. The corresponding cross-sections are comparable to those of high-column density hydrogen absorbers, suggesting that most atomic hydrogen at these redshifts has now also been detected in emission. Our observations provide direct insights into the spatial distribution of at least partly neutral gas in the circumgalactic medium of low mass galaxies at z > 3. I also discuss some implications for the demographics of high-redshift galaxies.

13/11/19 (Wednesday)
11:00, Library (ESO, Vitacura) | ESO Santiago
Special Talk
Talk — Pay it forward
Julien Milli (ESO & IPAG, FR)

## Abstract

After 7 years at ESO-Chile, I am about to return to France joining the IPAG Institute of Astrophysics in Grenoble as assistant astronomer. In the spirit of the «Pay it forward » talk series,  I would like to use my non-linear career path to highlight the impact of the decisions I made on my career, and provide some examples of what can be done at ESO and after ESO for early-career researchers.

11/11/19 (Monday)
12:00, Library (ESO, Vitacura) | ESO Santiago
TMT (30 minutes talk)
Talk — Formation imprints in the kinematics of the Milky Way globular cluster system
Andres Piatti (Universidad Nacional de Cordoba, AR)

## Abstract

We report results on the kinematics of Milky Way globular clusters
based on updated space velocities for nearly the entire globular cluster population.
We found that a 3D space with the semi-major axis, the eccentricity and the inclination of
the orbit with respect to the Milky Way plane as its axes is helpful in order to dig into
the formation of the globular cluster system. We find that globular clusters formed in-situ show a clear
correlation between their eccentricities and their orbital inclination in the sense
that clusters with large eccentricities also have large inclinations. These globular clusters also
show a correlation between their distance to the Milky Way center and their eccentricity.
Accreted globular clusters  do not exhibit a relationship between eccentricity and inclination,
but span a wide variety of inclinations at eccentricities larger than ~ 0.5.
These findings can be explained if globulars formed from gas that collapsed radially in the outskirts, with
preference for relative high infall angles. As the material reached the rotating
forming disk, it became more circular and moved with lower inclination relative to the
disk. A half of the globular cluster population was accreted and deposited in orbits covering the
entire range of energies from the outer halo to the bulge.
08/11/19 (Friday)
12:00, Library (ESO, Vitacura) | ESO Santiago
TMT (30 minutes talk)
Talk — AGNs with MATISSE
Violeta Gamez (Leiden, NL)

## Abstract

Interferometry in the mid infrared benefits from several advantages for
the study of the cores of AGNs, namely optimum access to the innermost
dusty regions that lie very close to the central blackhole and a much
higher resolution compared to single dish telescopes. Already with MIDI
the old model of the dusty toroidal structure was challenged by
unveiling  substantial extended IR emission in the most unexpected
directions. MATISSE, the latest instrumentation in this field, expands
the reach of MIDI further into and beyond the mid-IR to the L and M
bands, adds more spectroscopic potential and aims at fully exploiting
multiple-baseline interferometry with the VLTI allowing, for the first
time, image reconstruction. This talk describes MATISSE and the first
results from  the commissioning data.

## October 2019

30/10/19 (Wednesday)
15:30, Library (ESO, Vitacura) | ESO Santiago
ESO Colloquium
Talk — The TOPoS project
Elisabetta Caffau (GEPI - Observatoire de Paris)

## Abstract

The extremely metal-poor (EMP) stars hold in their atmospheres the fossil record of the
chemical composition of the early phases of the Galactic evolution. The chemical analysis
of such objects provides important constraints on these early phases of the Universe.
EMP stars are very rare objects; to dig them out large amounts of data have to be processed.
With an automatic procedure, we analysed from the Sloan Digital Sky Survey spectra of objects
with the colours of Turn-Off stars in order to select a sample of good EMP star candidates.
During the ESO Large Programme TOPoS and the French-Italian GTO of the spectrograph X-Shooter,
we observed a sample of these candidates.
We could confirm the low metallicity of our sample of stars and we succeeded in finding and analysing several very interesting objects.

29/10/19 (Tuesday)
12:00, Library (ESO, Vitacura) | ESO Santiago
TMT (30 minutes talk)
Talk — Deciphering a Lyman alpha Blob with deep MUSE observations
Christian Herenz (ESO)

## Abstract

Lyman α blobs (LABs) are extended (>100 kpc) radio-quiet Lyman α emitting nebulae that
reside in high-z proto-cluster environments.  Studies of LABs provide insights into early
galaxy formation processes within rare massive halos.  We analysed the distribution, the
ionisation state, and the kinematics of the Lyman α emitting gas in a prototypical z=3.1
LAB using 18h MUSE observations.  This data allowed to spatially pinpoint various gas
excitation mechanisms: ionising radiation and feedback effects close to known galaxies
within the blob and Lyman α scattering at larger distances.  The detection of HeII
emission far from star-forming systems in the blob hints at cooling radiation.  Moreover,
the angular momentum vector of the gas is found to be parallel with the blobs major axis.
This alignment appears at odds with average expectations from cosmological simulations but
likely relates to the unique environment in which the blob resides.

25/10/19 (Friday)
12:00, Urania room (ESO, Santiago) | ESO Santiago
TMT (30 minutes talk)
Talk — The major mechanism to drive turbulence in star-forming galaxies
Xiaoling Yu (Nanjing University/ESO)

## Abstract

We observed a representative local star-forming galaxy sample using Wide Field Spectrograph (WiFeS). The targets are selected from the xCOLD GASS survey, which provides well-measured molecular and atomic gas masses. We measured the intrinsic velocity dispersions of Ha emission line. By combining with other high z and low z star-forming galaxies, we found there is a good correlation between the velocity dispersion and star formation rate. Combining the advantages of Integrated Field Unit (IFU) observations by WiFeS and gas masses measurement by xCOLD GASS survey, comparing our results with predictions of theoretical models, we found that transport+feedback model can explain the observed relationship between velocity dispersion and star formation rate. Transport dominates the turbulence of high z and high SFR star-forming galaxies.

23/10/19 (Wednesday)
11:30, Library (ESO, Vitacura) | ESO Santiago
ESO Colloquium
Talk — Carbon Enhanced Metal-Poor (CEMP) stars, primordial stars or result of binary evolution ?
Piercarlo Bonifacio (GEPI - Observatoire de Paris)

## Abstract

Stars with prominent spectral features, due to carbon-bearing molecules
constituted one of the four spectral types first defined by Angelo
Secchi in 1868. In the second half of the XX  century, as people
began to understand that the Galaxy is made up of stars of different metal
content it became  also evident that stars with prominent
features of carbon-bearing molecules became more frequent among stars of low metallicity. At the beginning of the XXI century we began to refer to
these stars as Carbon Enhanced Metal-Poor stars.
I will review the current observational status of these stars
and their astrophysical significance. It is interesting to note that
among the 14 currently known stars with iron content [Fe/H]< -4.5
12 are carbon enhanced. I shall discuss the implications of this
fact trying to illustrate the different views that emerge.
18/10/19 (Friday)
12:00, Library (ESO, Vitacura) | ESO Santiago
TMT (30 minutes talk)
Talk — Linking galaxies in emission and absorption systems at z~3
Ruari Mackenzie (ETH Zurich)

## Abstract

Understanding the connection between reservoirs of neutral hydrogen and star-forming galaxies at high redshift has long been the subject of observational and theoretical study. I will present the results of a survey of six z~3 Damped Lyman alpha systems with MUSE, to search for associated galaxies and to probe their environments. The detected systems include a very metal poor DLA which is revealed to be embedded in a filamentary structure spanning 400 kpc. We compare our results to the EAGLE hydrodynamical simulations and a semi-analytic model, to interpret the observed galaxy distributions statistically. By studying the mean environment of the absorbers we can constrain the properties of host galaxies, even if they are not detected directly. We conclude that our results are both compatible with galaxy-formation simulations and the large-scale clustering of DLAs, supporting a picture where DLAs have a characteristic halo mass of 10^11-10^12 solar masses. I may also present ongoing work on high redshift quasar nebulae, specifically trying to unravel the emission mechanism by studying much fainter quasars.

16/10/19 (Wednesday)
12:00, Library (ESO, Vitacura) | ESO Santiago
TMT (30 minutes talk)
Talk — 3D Kinematics of Stellar Substructures in the Magellanic Periphery
Lara Cullinane (Australian National University, Canberra, Australia)

## Abstract

The Large and Small Magellanic Clouds (LMC/SMC), as two of the closest and most massive satellites of the Milky Way, have significant effects on the local Universe; including the distribution of ultra-faint satellites, and the orbits of tidal streams. Ongoing survey efforts with the Dark Energy Camera have revealed a wealth of low-surface-brightness stellar substructures in the periphery of the Clouds; characterising these structures will provide significant insight into the currently poorly-constrained masses and interaction history of the Clouds. In order to elucidate the properties of the structures, we have used 2df+AAOmega at the Anglo Australian Telescope to instigate a large-scale spectroscopic follow-up of stars across the Magellanic periphery. We are able to detect the kinematic signature of the Clouds up to projected distances of 23 degrees from the centre of the LMC. Combining our spectroscopically derived radial velocities with Gaia DR2 astrometry provides the first 3D kinematics for these regions. Our initial set of measurements, along a large substructure to the north of the LMC, reveal velocities near the extremity of the substructure are significantly different from those expected from an extrapolation of the LMC rotation curve. Our ultimate aim is to use these 3D kinematics to assess dynamical models of the Clouds; this will shed new light on the origin of the substructures, and the evolution of the Magellanic/Milky Way system.

15/10/19 (Tuesday)
12:00, Library (ESO, Vitacura) | ESO Santiago
TMT (30 minutes talk)
Talk — Rapid Reionization by the Oligarchs: The Case for Massive, UV-Bright, Star-Forming Galaxies with High Escape Fractions
Rohan Naidu (Harvard-CfA, USA)

## Abstract

The protagonists of cosmic reionization remain elusive. Faint star-forming galaxies are considered leading candidates because they are numerous and may have significant ionizing photon escape fractions. In this talk I will update this picture relying on latest constraints on the reionization timeline from z>7 quasars & LyA emitters, and on the escape fraction from deep HST UV imaging. I will argue that the rapid timeline of reionization (300 Myrs, between z=6-8) and the high star-formation surface density of galaxies with significant escape fractions favor reionization driven by MUV<-18 galaxies. In fact, faint sources (MUV>-16) must be relegated to a limited role to ensure high neutral fractions at z=7-8. In this updated picture, the drivers of reionization do not lie hidden across the faint-end of the luminosity function, but are already known to us. I will outline strategies to test this scenario with current and future facilities.

14/10/19 (Monday)
12:00, Urania room (ESO, Santiago) | ESO Santiago
TMT (30 minutes talk)
Talk — SPIAKID
Piercarlo Bonifacio (GEPI - Observatoire de Paris)

## Abstract

In this talk I will describe the SPIAKID project, that will start on January 1st 2020 at Observatoire de Paris, financed by the European Research Council.
The goal of the project is to build a spectrophotometric imager, to be deployed at the focus of an 8-10m class telescope (VLT and/or GTC), with Kinetic Inductance Detectors (KIDs). In KIDs the pixels are based on a super-conducting LC oscillating circuit. The arrival of a photon breaks Cooper-pairs in the superconductor and alters the frequency, amplitude and phase of the oscillation. From this information one can reconstruct the time of arrival of the photon and its energy. Thus one can do spectrophotometry without use of dispersing elements or filters. In a KID detector all pixels are read in parallel at a very fast rate (< 1 ms), this opens the possibility of using speckle-imaging techniques to obtain also a very high angular resolution, in principle up to the diffraction limit of the telescope. SPIAKID has a well defined science goal: the study of the stellar populations
in Ultra faint Dwarf galaxies in the Local Group. This case will drive the instrument design. There are however many ancillary science cases that can be pursued and that I will describe briefly. I will describe the technical developements made so-far at the Observatoire de Paris and the path forward for the SPIAKID project. The goal is to be on the sky in 2024.

11/10/19 (Friday)
12:00, Urania room (ESO, Santiago) | ESO Santiago
TMT (30 minutes talk)
Talk — Finding the biggest flares from the smallest stars with the Next Generation Transit Survey
James Jackman (University of Warwick)

## Abstract

Stellar flares are explosive phenomena which, along with providing a way to probe the magnetic environments of stars, may seriously affect the habitability of planets around them. This is particularly true for M stars (e.g. Proxima Centauri, TRAPPIST-1) which host Earth-sized planets in their close proximity “habitable zone”, yet regularly flare with energies greater than the largest Solar flares. In this talk I will present our study of stellar flares using the 13 second cadence full frame images of the Next Generation Transit Survey (NGTS). The high cadence of NGTS allows to detect short duration flares missed by other surveys, while the full frame images means we can detect flares from both bright stars and ultracool M and L dwarfs which only become visible while flaring. Our work includes studying how flare properties change from G stars down to ultracool dwarfs and how flare occurrence rates change both between spectral types and as a function of age. I will also show how our work is greatly increasing the studied sample of flaring ultracool dwarfs and includes the
10/10/19 (Thursday)
12:00, Library (ESO, Vitacura) | ESO Santiago
TMT (30 minutes talk)
Talk — BASS-MUSE - An IFU follow-up of X-ray selected AGN in the low redshift universe
Nathen Nguyen (ESO - Universidad de Chile)

## Abstract

The BAT AGN Spectroscopic Survey (BASS) is an all-sky survey which excels at selecting unbiased, low-redshift and ultra-hard X-ray sources (14-195 keV).  Although the X-ray data provides an overview of the black hole properties of the low redshift AGN (z < 0.2), it lacks information on whether the activity of the black hole has any impact on the host galaxy on kiloparsec scales. Using the IFU capabilities of MUSE, we will be able to study the morphology and kinematics of the ionized gas within the host galaxies of the BASS sample. The project also tried to answer whether the activity of the AGN, inferred from the X-rays, influences the ionized gas distribution across various scales within the galaxy. In this talk, I will present the BASS-MUSE sample, its reduction and preliminary analysis. I will show the results from these analysis such as the stellar velocity maps and ionized gas distribution, where a few galaxies show spectacular AGN driven outflows.

03/10/19 (Thursday)
12:00, Library (ESO, Vitacura) | ESO Santiago
TMT (30 minutes talk)
Talk — Closing the loop: Spectroscopic observations of the machine learning selected anomaly catalogue from AllWISE Sky Survey
Aleksandra Solarz (ESO)

## Abstract

Wide-angle photometric surveys of previously uncharted sky areas or wavelength regimes will always bring in unexpected sources whose existence and properties cannot be easily predicted from earlier observations. Such objects can be efficiently sought for with novelty detection algorithms. I will present an application of such a method, called one-class support vector machines (OCSVM), to search for anomalous patterns among sources pre-selected from the mid-infrared AllWISE catalogue  covering the whole sky.  OCSVM successfully finds artifacts, such as objects with spurious photometry due to blending, but most importantly also real sources of genuine astrophysical interest. Among the latter, OCSVM has identified a sample of heavily reddened AGN/quasar candidates distributed uniformly over the sky and in a large part absent from other WISE based AGN catalogues. A campaign to reveal the nature and verify the performance of the algorithm was conducted with EFOSC2 and SofI instruments on NTT. In this talk I will present the results of the observations and their implications.

02/10/19 (Wednesday)
15:30, Urania room (ESO, Santiago) | ESO Santiago
ESO Colloquium
Talk — A contribution of star-forming regions and satellites to the z ~ 2 galaxy mass assembly
Anita Zanella (ESO)

## Abstract

Giant star-forming regions ("clumps") with sizes < 1 kpc, masses ~ 10^9 Msun and blue colors are ubiquitous features of z ~ 2 galaxies. However, their formation phase has never been observed and their fate is highly uncertain. Are they born in-situ due to fragmentation of gas-rich disks or are they small companion galaxies that merged with the host? Do they migrate inward and contribute to the formation of the galaxy bulge or are they rapidly disrupted by stellar feedback?
To address these issues we are studying ~50 clumpy galaxies at z ~ 2, observed with ultra deep HST/WFC3 imaging and slitless spectroscopy. From spatially resolved emission line maps we discovered a bright, newly formed clump, in the very early phase of its collapse (age < 10 Myr). With a specific SFR ~ 30 times higher than the one of the whole galaxy, it behaves like a mini-starburst, showing that in-situ violent disk instability can induce highly efficient star formation. Our estimate of the clumps' lifetime (~ 500 Myr) favours scenarios where they survive stellar feedback and suggests that their inward migration is a plausible mechanism to form the bulge of the galaxy. I will also discuss the analysis of older clumps: their formation rate and age distribution as a function of distance from the galaxy nucleus put further constraints on their lifetime, the strength of stellar feedback, and their role in galaxy evolution.

01/10/19 (Tuesday)
12:00, Library (ESO, Vitacura) | ESO Santiago
TMT (30 minutes talk)
Talk — Revealing Magellanic stars in the Milky Way halo
Camila Navarrete (ESO)

## Abstract

The Large and Small Magellanic Clouds are a pair of nearby, likely rather massive dwarf galaxies. Located at 50 and 60 kpc from us, at the moment they are located well within the halo of the Milky Way. Despite its importance, the epoch of their accretion, their binary lifetime, their masses and spatial extent are largely unconstrained. This uncertainty poses a serious challenge to our attempts to reconstruct the properties of the Milky Way from the observables delivered by the ESA's Gaia satellite. In this talk, I will present the results from two spectroscopic campaigns carried out with FORS2@VLT aimed to uncover the kinematic signature of Magellanic stars in the Milky Way halo. In particular, I will describe the study of stellar streams in 4D surrounded the Clouds and the implication for the spatial extent of the halo of the LMC as well as the past ineraction of the LMC and SMC; and present the first results tracing stars from the predicted Magellanic "wake", one of the most striking implications of the massive Magellanic in-fall in the halo of our Galaxy.

## September 2019

27/09/19 (Friday)
12:00, Urania room (ESO, Santiago) | ESO Santiago
TMT (30 minutes talk)
Talk — Multi-wavelengths observations of very inclined protoplanetary disks: probing dust vertical settling
Marion Villenave (ESO)

## Abstract

The diversity of physical and structural conditions in protoplanetary disks – the birthplace of planets – might be responsible for the diversity observed in the exoplanet population. Studying protoplanetary disks could thus provide indirect constraints on planet formation processes. During this talk, I will present multi-wavelengths images of several protoplanetary disks that I analyzed during my 2-years studentship at ESO. The comparison of optical/infrared images, tracing small micron grains, with millimeter data, originating from the larger millimeter grains, provides crucial information on the efficiency of some evolutionary mechanisms. In particular, we explore dust vertical settling by observing a sample of 12 edge-on disks. These disks offer a unique orientation, allowing to observe directly the vertical structure of disks. We find that the vertically resolved disks sufficiently edge-on are compatible with having a millimeter dust scale height of about 1au at 100au, indicative of very efficient settling. This increasing dust density in the midplane likely enhance the efficiency of planet formation.

26/09/19 (Thursday)
12:00, Urania room (ESO, Santiago) | ESO Santiago
TMT (30 minutes talk)
Talk — Photochemical reduction of CO2 on terrestrial planets
Svatopluk Civiš (J. Heyrovský Institute of Physical Chemistry, Czech Academy of Sciences)

## Abstract

The chemical evolution of early terrestrial planets is a long standing enigma which involves the uncertainty of chemical atmospheric composition and plausibility of biomolecules synthesis. In this study, new alternative scenario of the origin of methane on Mars and terrestrial planets is suggested. Martian and other planetary atmospheres rich in carbon dioxide can be abiotically converted into a mixture of methane and carbon monoxide by ‘methanogenesis’ on porous mineral photoactive surfaces upon soft UV irradiation. On young planets exposed to heavy bombardment by interplanetary matter, the process can be followed by synthesis of biomolecules in reprocessing of such reactive reducing atmosphere by impact-induced shock waves. The proposed mechanism of methanogenesis may help answer the question on the formation of methane and carbon monoxide by photochemical processes, the formation of biomolecules on early Earth and other terrestrial planets, and the source and seasonal variation of methane concentrations on Mars.

24/09/19 (Tuesday)
12:00, Urania room (ESO, Santiago) | ESO Santiago
TMT (30 minutes talk)
Talk — The origin of brown dwarfs
Alejandro Santamaria Miranda (Universidad de Valparaiso)

## Abstract

The main formation mechanism of brown dwarfs is still under debate. While the latest discoveries point towards a scaled-down version of the star formation process, other models, such as embryo ejection or stellar disk fragmentation, are still not unequivocally discard. Using different techniques, as spectroscopy and interferometry at different wavelength, we study different evolution stages of brown dwarf formation. First, I present our ALMA cycle 3 (band 6) continuum observations of Lupus 1 and 3 star formation regions, based on previous ASTE/AzTEC observations and a set of previously known class II substellar objects from the literature. We found eleven pre-substellar cores candidates that seems to be in gravitational contraction, and two protobrown dwarf candidates. We also measured the dust disk masses of six Class II brown dwarfs, and their properties are consistent with being scaled down versions of forming low mass stars. Second, we discovered the base of a bipolar molecular outflow in a very low mass star (Par-Lup3-4), whose properties seem to be scaled-down from the low mass star regime. Third, we study the accretion rate of the substellar companion to the stellar binary system; its accretion is in agreement with an extension of the relation obtained from more massive objects.
10/09/19 (Tuesday)
12:00, Urania room (ESO, Santiago) | ESO Santiago
TMT (30 minutes talk)
Talk — Exoplanet detection in direct imaging by statistical learning of the non-stationary patch covariances: The PACO-based algorithms
Olivier Flasseur (CNRS/INSU, Grenoble, France)

## Abstract

We have recently introduced a new method dedicated to source detection from angular differential imaging (ADI) data:

PACO (for PAtch COvariances). Data reduction in ADI is challenging because the faint point sources are hidden in a stronger

nonstationary background (speckles) displaying strong spatial correlations. PACO learns locally a statistical model of the

background directly from the data. This model captures short-scale spatial correlations up to a separation of ten pixels (i.e.,

within an image patch). The decision in favor of the presence or the absence of an exoplanet is then performed by a binary

hypothesis test. PACO offers appealing characteristics compared to existing detection approaches. Since no image subtraction is performed,

the photometry is preserved. PACO is completely parameter-free, including the computation of a detection map, its thresholding

to extract meaningful detections, and the estimation of fluxes of the detected sources. Finally, the resulting detection

maps are stationary and statistically well-modeled so that the false alarm rate, the probability of detection, and the contrast

can be directly assessed without post-processing and/or Monte-Carlo simulations. We have shown using datasets from the

VLT/SPHERE-IRDIS instrument that the proposed method achieves significantly better detection performance than current

cutting-edge algorithms such as TLOCI or KLIP. We believe that these significant practical advantages should make PACO a

method of choice for the analysis of ADI observations, in particular for large exoplanet surveys.

We have very recently extended this algorithm to the joint processing of the different spectral channels of angular

and spectral differential imaging (ASDI) data. The resulting algorithm, named PACO-ASDI, accounts for the spatio-temporospectral

fluctuations of the data. Our tests conducted on several ASDI datasets from the VLT/SPHERE-IFS instrument

show that PACO-ASDI also produces reliable detection maps and unbiased spectral energy distribution of the detected sources

(with confidence intervals), outperforming the state-of-the-art exoplanet hunter algorithms.

09/09/19 (Monday)
12:00, Urania room (ESO, Santiago) | ESO Santiago
TMT (30 minutes talk)
Talk — Constraining the formation of the large Nuclear Star Cluster of FCC47 with MUSE + AO
Katja Fahrion (European Southern Observatory)

## Abstract

Nuclear star clusters (NSCs) are found in at least 70% of all galaxies; however, despite their abundance it is still debated how they form. The currently discussed scenarios propose that NSCs could either form from infalling gas directly at the galactic center or through the accretion of globular clusters (GCs) that spiral inwards due to dynamical friction, but also a composite scenario is possible. In the GC accretion scenario, the NSC would reflect the low angular momentum and low metallicities of the surrounding GC population, whereas the in-situ scenario would lead to a higher angular momentum and higher metallicities from subsequent star bursts.

Constraining NSC formation in galaxies therefore requires a complete view of both the kinematics and chemical properties of the host galaxy, the NSC and the GC system. To achieve this task, we use IFU data from the MUSE instrument of the early-type galaxy FCC47, which has a remarkably large NSC (Reff ~ 66 pc) and a very rich GC system.

In addition to an analysis of the galaxy light kinematics and stellar population properties, we extract optical spectra of the GCs to determine radial velocities and metallicities. In combination with a dynamical model, our panoramic view of the galaxy and its star clusters allows to put constraints on the formation of FCC47’s massive NSC.

04/09/19 (Wednesday)
12:00, Urania room (ESO, Santiago) | ESO Santiago
TMT (30 minutes talk)
Talk — An updated census of spectroscopic binary system in the young associations
Sebastián Zúñiga-Fernández (ESO)

## Abstract

The young associations offer us one of the best opportunities to study the properties of young stellar and sub-stellar objects thanks to their proximity (< 200 pc) and age (~ 5 - 150 Myr). We update the spectroscopic binary fraction of the SACY (Search for Association Containing Young stars) sample using rotational broadering and higher-order cross-correlation features (CCFs). Using high-resolution spectroscopic observations we obtain 1375 CCFs for our calculation of radial and rotational velocities, these values were cross-matched with previously published values. Out of 427 objects, we flagged 68 potential spectroscopic multiple (SB) systems. The results of our new radial velocities determinations and SBs candidates are particularly relevant for membership revision of targets in young stellar associations. Our results show that the three highest spectroscopic binary fractions correspond to three youngest associations (Etha-Cha: 0.23, TW Hydrae: 0.20 and Beta-Pic:0.23). We comment on the significance of the resulting SB fraction for futher investigations and the implications on companion migration beyond ~20 Myr.

## August 2019

30/08/19 (Friday)
11:00, Licancabur meeting room | ESO Santiago
JAO Colloquium
Talk — Geomatics for site monitoring and weather forecasting at APEX, ALMA and Paranal Observatories
Juliette Ortet (ALMA/APEX visitor)

## Abstract

Contraction of the terms "geography" and "computer science", Geomatics, is a set of technologies for modeling, representation and analysis of the surrounding environment. Remote sensing and meteorological data processing can be applied to the sites of astronomical facilities in order to improve, for instance, the scheduling of observations as well as the calibration of astronomical data. A couple of past and ongoing projects will be presented in order to highlight the perspectives of geomatics studies applied to ESO observatories. These efforts benefits mainly APEX, ALMA and Paranal, but can also be adapted and conceived globally for all astronomical facilities in the world.

29/08/19 (Thursday)
16:00, Licancabur meeting room | ESO Santiago
JAO Colloquium
Talk — ALMA polarization observations toward protoplanetary disks
Satoshi Ohashi ((RIKEN, Tokyo, Japan))

## Abstract

Protoplanetary disks (PPDs) are believed to be birth places of planets. Recent high resolution ALMA observations have shown prominent structures such as multiple rings and crescents. In order to understand the physical and chemical properties of PPDs, dust continuum and molecular line observations have been carried out with ALMA.  Here, we introduce another observing mode, which is the polarization of dust continuum emission.  The mechanisms of the polarization have been discussed with great attention since ALMA succeeded in detecting the polarized emission from the protoplanetary disk of HD 142527 (Kataoka et al. 2016).  Taking into account the grain growth in PPDs, the polarization is possibly produced by scattering or grain alignment with magnetic fields, radiation, or gas flow.  Understanding the polarization mechanisms allows us to reveal the physical conditions of PPDs such as dust grain size, dust scale height, or magnetic field structure.  In this talk, I will show recent results of ALMA polarization observations. In particular, I focus on the two different morphology disks (a lopsided disk and multiple rings).  For the lopsided disk of HD 142527, we found different polarization mechanisms of self-scattering and magnetic fields between north and south regions.  These different polarizations can be understood by different grain size distributions (Ohashi et al. 2018). The magnetic fields are toroidal.  For the multiple rings of HD 163296, we found that the polarization is produced by self-scattering. The dust grains are 140 micron in the gaps, while those are much larger (or smaller) in the rings.  Furthermore, the dust scale height needs to be less than one-third of the gas scale height inside the 70 au ring, while it reaches two-thirds of the gas scale height outside of the 70 au ring.  Then, we can constrain the gas turbulence to be $\alpha\lesssim1.5\times10^{-3}$ at the 50 au gap and $\alpha\sim 0.015-0.3$ at the 90 au gap, respectively.  The transition of the turbulent strength at the boundary of the 70 au ring may indicate the existence of the dead zone (Ohashi & Kataoka, submitted to ApJ).

28/08/19 (Wednesday)
15:30, Urania room (ESO, Santiago) | ESO Santiago
ESO Colloquium
Talk — Five years of SPHERE guaranteed time observations: harvest and prospects
Gael Chauvin (Grenoble)

## Abstract

With the development of direct imaging techniques and instruments, vast efforts have been devoted
during the past decade to image lighter, cooler and closer companions to nearby stars, and ultimately exoplanetary
systems. Complementary to other planet-hunting techniques, direct imaging has opened a new astrophysical window to explore the physical
properties and the formation mechanisms of giant planets. In this context, SPHERE, the extreme adaptive optics,
coronagraphic and differential spectro-imager facility at the VLT, has greatly contributed to the exploration
of new and known planetary systems in direct imaging. In 5 years of operation, SPHERE has revealed stunning
details of young proto-planetary and debris disks. It has enabled to characterize the orbital, atmospheric,
and demographic properties of young giant planets between 10 and 100 au to complete our current view and
understanding of the mechanisms of formation and evolution of giant planets. The versatility of SPHERE has
also enabled various secondary and sometimes unexpected science cases (solar system, stellar physics,
extra-galactic) owing to its exquisite image quality, a large spectral coverage from the visible to the
near IR, and the availability of various observing modes (imaging, spectroscopy and polarimetry). In this talk,
after describing the SPHERE instrument and performances, I will present the key scientific results and
lessons learned from the SPHERE Guaranteed Time Observations now almost finished, and present the SPHERE+ project.
SPHERE+ has been recently proposed to open a new, genuine scientific window to explore the bulk of the giant planet
population close to the snow line in synergy with other facilities like high-resolution spectrographs
(CRIRES+, NIRPS, ESPRESSO), ALMA, or the ELT from the ground, and GAIA, JWST and WFIRST from space.

27/08/19 (Tuesday)
12:00, Library (ESO, Vitacura) | ESO Santiago
ESO Thirty Minute Talks
Talk — A meta analysis of 56Ni masses from core-collapse supernovae
Joe Anderson (ESO)

## Abstract

A fundamental property determining the transient behaviour of core-collapse supernovae (CCSNe) is the amount of radioactive 56Ni synthesised in the explosion. Using established methods, this is a relatively easy parameter to extract from observations. Here I present a meta analysis of all published 56Ni masses for CCSNe. Collating a total of 258 literature 56Ni masses I compare distributions of the main CC SN types: SNe II; SNe IIb; SNe Ib; SNe Ic; and SNe IcBL. On average, stripped-envelope SNe (SE-SNe: IIb; Ib; Ic; and Ic-BL) have much higher values than SNe II. These observed distributions are compared to those predicted from explosion models. While the SN II distribution follows model predictions, the SE-SNe have a significant fraction of events with 56Ni masses much higher than predicted, implying significant differences in the progenitor structures and/or explosion properties between SNe II and SE-SNe. However, such distinct progenitor and explosion properties are not currently favoured in the literature. Alternatively, the popular methods used to estimate 56 Ni masses for SE-SNe may not be accurate. I discuss possible issues with these methods and the implications of true 56Ni mass differences on progenitor properties of different CC SNe.

22/08/19 (Thursday)
16:00, Licancabur meeting room | ESO Santiago
JAO Colloquium
Talk — ALMA Studies of Young Eruptive Stars
Antonio Hales (JAO)

## Abstract

It is now believed that stars acquire most of their mass in short episodes of accretion outbursts. This episodic accretion picture has replaced the traditional steady state accretion model and is changing our understanding on how stars gain their mass (and the origin of the IMF), binary formation, planet formation, the luminosity spread in young clusters, disk chemistry and snowline migration.  Despite its relevance, the physical mechanisms responsible for episodic accretion remain poorly understood. In this talk I will review recent observational and modelling advancements aimed at constraining the physical properties of outbursting sources to help understand what drives this important phase of star formation.

21/08/19 (Wednesday)
12:00, Library (ESO, Vitacura) | ESO Santiago
TMT (30 minutes talk)
Talk — Supernova Remnant Puppis A: What is There and What is not There
Janette Suherli (Wesleyan University, USA)

## Abstract

We study the Galactic SNR Puppis A data obtained by the Multi-Unit Spectroscopic Explorer (MUSE) integral field spectrograph at the Very Large Telescope (VLT), through an unusual mean of observation conditions (PI: Vogt). In this talk we will briefly introduce the SNR study and how integral field spectroscopy has impacted the SNR research; then we will summarize our observation and analysis methods; finally we will discuss our findings and its implications.

20/08/19 (Tuesday)
12:00, Urania room (ESO, Santiago) | ESO Santiago
ESO Thirty Minute Talks
Talk — Stellar winds pump the heart of the Milky Way
Diego Calderón (Instituto de Astrofísica, Pontificia Universidad Católica de Chile)

## Abstract

The central super-massive black hole of the Milky Way, Sgr A*, accretes at a very low rate making it a very underluminous galactic nucleus. Despite the tens of Wolf Rayet stars present within the inner parsec supplying ~10^{-3} Msun/ yr in stellar winds only a negligible fraction of this material ends up being accreted onto Sgr A*. The recent discovery of cold gas (~10,000 K) in its vicinity raised questions about how such material could settle in the hostile environment near Sgr A*. In this work we show that the system of mass-losing stars blowing winds can naturally create a cold, disk-like structure when modeled for long enough timescales. To do so, we run hydrodynamical simulations using the grid-based code Ramses starting as early in the past as possible to observe the state of the system at the present time. Our results show that the system reaches a quasi-steady state in about ~500 yr with material being captured at a rate of ~10^{−6} Msun/yr at scales of ~10^{-4} pc consistent with the observations and previous models. However, on longer timescales (􏰀~3000 yr) the material tends to accumulate close to the black hole in the form of a disk. Considering the duration of the Wolf-Rayet phase, we conclude that this scenario likely has already happened, and could be responsible for the more active past of Sgr A*, and/or its current outflow. We argue that the hypothesis of the mass-losing stars being the main regulator of the activity of the black hole deserves further consideration.

13/08/19 (Tuesday)
12:00, Library (ESO, Vitacura) | ESO Santiago
TMT (30 minutes talk)
Talk — Light in the Suburbs: structure and chemodynamics of galaxy halos
Johanna Hartke (European Southern Observatory)

## Abstract

In my talk, I will give a summary of this year's galaxy halos conference "Light in the Suburbs" that took place in Sexten in June. Due to the long dynamical timescales in galaxy halos, we can make inferences about the initial dynamic conditions under which galaxies like our own Milky Way formed through the study of their dynamics. This more than half a century old statement from Eggen, Lynden-Bell and Sandage illustrates very clearly the motivation to study the dynamics and chemical composition of stars in the halos of galaxies and their implication for the models of galaxy formation.

Measuring the physical properties of the structural components of the galaxy halos with imaging and spectroscopic surveys from the ground and space allows us to trace back the formation history of these components. We can also assess the relative importance of the competing mechanisms, i.e. the accretion of stellar systems, and the dissipative collapse of the galaxies’ gas. In a hierarchical universe both processes operate simultaneously, on different time-scales across galaxies, so to understand galaxy assembly we need to compare observations against theoretical simulations of structure formation, which follow the interplay between the complex physical process (merging, gas flows, AGN formation, feedback) that lead to the formation of different structural components seen in our own Milky Way as well as in external galaxies. I will conclude the talk with a spotlight on my conference contribution on the surprisingly metal-poor halo of the early-type galaxy M49 in the Virgo Cluster.

09/08/19 (Friday)
12:00, Urania room (ESO, Santiago) | ESO Santiago
ESO Thirty Minute Talks
Talk — Chemical Abundances from Integrated Light of Stellar Clusters
Soeren Larsen (Department of Astrophysics/IMAPP, Radboud University)

## Abstract

I will discuss our on-going project to measure detailed chemical abundances from integrated-light spectra of stellar clusters. The aims are two-fold, namely: 1) to employ clusters as probes of chemical enrichment histories in galaxies that are too distant for individual stars to be studied in detail, and 2) to constrain the presence of chemical abundance anomalies (“multiple populations”) in clusters in various environments and of various ages. To first order, GCs in Local Group dwarfs, M31, M33, and the Milky Way display remarkably homogeneous abundance patterns, with a scatter of < 0.1 dex in the abundance ratios [Ca/Fe] and [Ti/Fe]. However, statistically significant variations are present for several elements, including [Na/Fe], [Ni/Fe], [Cu/Fe], [Ba/Fe]. The presence of elevated [Na/Fe] ratios point to the presence of multiple populations in massive clusters as young as 2-3 Gyrs, as is also supported by colour-magnitude diagrams of young massive clusters in the Magellanic Clouds.

08/08/19 (Thursday)
12:00, Urania room (ESO, Santiago) | ESO Santiago
ESO Thirty Minute Talks
Talk — Feeding the Giants: a Multiwavelength Perspective of the Environments of z~6 QSOs
Chiara Mazzucchelli (ESO)

## Abstract

Luminous quasars at high redshift (z>6, i.e. in the first Gyr of cosmic history), already hosting ~billion solar masses black holes, are formidable probes of the universe in the Epoch of Reionization. Theoretical models predict them to reside in biased regions, embedded in large galactic overdensities, as potential signposts of the first protoclusters. However, previous UV-based observations of such environments did not provide a clear picture.
Here, I will present our current, multi-wavelength study of the environment of quasars at high-z.
I will first report our search for Lyman Alpha Emitters and Lyman Break Galaxies around a quasar at z~5.7, using sensitive narrow- and broad-band imaging with FORS2/VLT.
I will also show follow-up, deep HST/WFC3 and Spitzer/IRAC observations of gas-rich, extremely star forming galaxies in four overdense quasars fields, firstly discovered with ALMA. I will build their spectral energy distributions, and compare them with both observations of local galaxies and models. I will derive compelling constraints on the contribution of their unobscured star formation and their stellar masses, and I will place them in the context of starbursts/starforming galaxies in the early universe.

07/08/19 (Wednesday)
12:00, Library (ESO, Vitacura) | ESO Santiago
ESO Thirty Minute Talks
Talk — Properties of metal-poor transitional and degenerate brown dwarfs
ZengHua Zhang (Paris Observatory)

## Abstract

The transition zone of unsteady hydrogen fusion is also the substellar transition zone that separates very low-mass stars, transitional and degenerate brown dwarfs. Transitional brown dwarfs (T-BD) have unsteady hydrogen fusion in their cores to replenish the dissipation of their initial thermal energy, thus have extremely slow cooling rate. Degenerate brown dwarfs (D-BD) are the majority of brown dwarfs, and have no energy supply from hydrogen fusion thus cool continuously. Metal-poor T-BDs of the Galactic thick-disk and halo spans a wide temperature range (~L3-T4) within a narrow mass range. Metal-poor D-BDs have become T5+ subdwarfs. I will discuss the spectral type-colour correlations, spectral type-absolute magnitude correlations, colour-colour plots, and HR diagrams of L and T subdwarfs, in comparison to these of L and T dwarfs. I will show how metal-poor brown dwarfs lead us to new interpretation of evolutionary models, which help us reach a better understanding of brown dwarf population. This talk is based on works published in a series titled 'Primeval very low-mass stars and brown dwarfs'.

## July 2019

23/07/19 (Tuesday)
15:30, Library (ESO, Vitacura) | ESO Santiago
TMT (30 minutes talk)
Talk — VLTI update and prospects for 2030
Xavier Haubois (European Southern Observatory)

## Abstract

After a status update on VLTI operations, I’d like to summarize the various VLTI projects that were presented
during "The VLT in 2030" conference that was held last month.
19/07/19 (Friday)
12:00, Urania room (ESO, Santiago) | ESO Santiago
TMT (30 minutes talk)
Talk — The core of the matter: directly resolving the inner structures of AGN with GRAVITY
Eckhard Sturm (MPE, Munich)

## Abstract

One of the most exciting opportunities offered by GRAVITY is to directly resolve the broad line region (BLR)
of active galactic nuclei using spectro-astrometry. Since P99 we have been exploiting this capability to study the
inner workings of AGN in the K-band on unprecedented micro-arcsecond (sub-pc) spatial scales. We have made
the ﬁrst interferometric detection of the BLR and found ordered rotation in the quasar 3C 273 (GRAVITY
collab., Nature, 2018) proving both the feasibility and value of such measurements. We are now taking
major steps forward by extending this capability to measure BLR radius, structure, and kinematics for a sample
of objects spanning four orders of magnitude in luminosity. We will establish a new, GRAVITY-based radius-
luminosity relation, thereby testing reverberation mapping methods and forming the basis for more robust
black hole mass measurements in large samples in the local and distant Universe. From the same data, we will
simultaneously measure the size and structure of the hot dust “torus” to understand its origin and physical
connection to the BLR.

18/07/19 (Thursday)
15:30, Urania room (ESO, Santiago) | ESO Santiago
ESO Colloquium
Talk — Imaging exoplanets and circumstellar disks: the current instruments and their limitations.
Dr Faustine Cantalloube (MPIA, Heidelberg)

## Abstract

Imaging exoplanets provides a tremendous amount of information about their formation process within their environment, their orbital motion and their atmospheric composition. However this is a challenging task to reach the very high-resolution (less than 500mas) and very high-contrast (less than 10^-6 in the near-infrared) required to detect exoplanets by imaging. To do so, specific ground-based instruments have been built worldwide, equipped with extreme adaptive optics systems and coronagraphs, delivering images on which advanced post-processing must be applied to unveil exoplanet companions. However the deeper we go in contrast, the more sensitive we are to small error terms that were hindered before and can now limit the contrast performance of the instrument. I will review these error terms based on the SPHERE images and emphasise on one of them: the wind driven halo. The wind driven halo originates from the high speed jet stream atmospheric layer. These considerations are driving the design of the next generation of high-contrast instruments for the ELT whose first light is foreseen in 2030.

17/07/19 (Wednesday)
15:30, Urania room (ESO, Santiago) | ESO Santiago
TMT (30 minutes talk)
Talk — Unveiling the nature of the XBONG 2PBC J1332.1-7751
Harold Peña (University of Turin, Italy and INAOE, Mexico)

## Abstract

X-ray bright optically normal galaxies (XBONG) are one of the most surprising discoveries of X-ray surveys. Even if the central source is bright in the x-rays and can be explained only with the presence of an AGN, the XBONG optical counterparts show spectral features typical of normal galaxies without any obvious signatures of nuclear activity (no broad, nor highly ionized emission lines). The origin of such naked AGN emission is unclear. Is the Narrow Line Region truly missing in these objects?
If yes, are XBONG fed by Radiatively Inefficient Accretion Flow? If not, are the optical emission lines buried by gas and dust or rather diluted in the galaxy starlight? And, beyond the answers, which is the impact of such optically-naked  but X-ray powerful AGN on the host galaxy?
To answer this questions I’ll show preliminary results I’m obtaining from the analysis of MUSE and KMOS property data.

12/07/19 (Friday)
12:00, Library (ESO, Vitacura) | ESO Santiago
ESO Thirty Minute Talks
Talk — ATACAMA : A broadband survey for Lyman alpha nebulae
Francis Tang (Kapteyn Institute, Groningen, NL)

## Abstract

Giant Lyα emitting nebulae, also known as Lyα ‘blobs’ (LABs), are likely sites of ongoing massive galaxy formation. The powering mechanism behind the strong Lyα emission in these nebulae as well as their origin is still poorly understood, in part because of the rarity of these sources. Most of the currently known LABs, specially the ones at high redshifts, are discovered using narrowband surveys, which limits the comoving volume that can be probed, and therefore limits the search to known galaxy overdensities.

I will present the ATACAMA project (PI : Hibon): a systematic search for LABs in a multi-wavelength broadband imaging data set, the tool developed for this quest, and the results I obtained during my 3-month internship .
11/07/19 (Thursday)
16:00, JAO Licancabur | ESO Santiago
JAO Colloquium
Talk — All you've ever wanted to know about the European ARC network (and possibly more!)
Evanthia Hatziminaoglou (ESO)

## Abstract

The European ARC network is an international, geographically dispersed structure, that consists of the central ARC at ESO, seven ARC nodes and one Centre of Expertise, distributed across Europe. It represents an organised effort to provide the European ALMA user community with uniform expert support from the stage of proposal preparation through to data reduction, in order to enable the optimal usage and increase the scientific output of ALMA. The talk will focus on the history of the network, it's structure, the funding and staffing situation, the coordination model, the tasks the nodes are involved in, their expertise, their past and current contribution to observatory tasks and other related matters.

12:00, Library (ESO, Vitacura) | ESO Santiago
ESO Thirty Minute Talks
Talk — Can the infrared emission of all Soft Gamma-Ray Repeaters and Anomalous X-ray Pulsars be explained by an irradiated disk?
Sarah Villanova Borges (INPE-Brasil)

## Abstract

Soft Gamma-Ray Repeaters and Anomalous X-ray Pulsars (SGR/AXPs) are isolated compact stars identified due to a characteristic quiescent soft X-ray emission. Their nature is still a question for debate and several emission mechanisms have been proposed, such as neutron star (NS) with super strong decaying magnetic field (magnetar model), accreting NSs, white dwarf (WD) pulsars and accreting WDs. Among its broad energy range, the infrared (IR) emission, exhibited by about 50 % of the class, is one of the most interesting. For the AXP 4U 0142+61, the IR emission is well modelled by a disk, corroborated by a possible silicate emission feature. For other SGR/AXPs, the lack of counterpart in several bands hampers the same conclusion and their origin is still debated. For isolated NS, the presence of disks is polemic, since IR emission is an extremely rare feature and no other isolated NS have confirmed debris disk. On the other hand, at least 27 % of WDs presents traces of high elements that only could be explained by the accretion of material from planetary discs. Thus, confirming the presence of a disk as a intrinsic property of the class has deep consequences in the discussion of its nature. Here, we investigate whether the disk emission can be expanded for the entire class. We study the IR emission of SGR/AXPs in order to find a correlation between their luminosities in the Ks-band and X-rays. Our results are consistent with an irradiated disk, which reinforces the possibility of those objects to be WDs.

10/07/19 (Wednesday)
12:00, Library (ESO, Vitacura) | ESO Santiago
TMT (30 minutes talk)
Talk — Investigating the link between the bulge growth and quenching through the analysis of bulge and disk properties in CANDELS
Paola di Mauro (Sorbonne Universit´e, Observatoire de Paris, Universit´e PSL, CNRS, LERMA, F-75014, Paris, France)

## Abstract

Passive and star forming galaxies have different morphologies and structures, suggesting the existence of a connection between the star formation activity and the formation/growth of internal components. Despite the numerous efforts, the details of how galaxies form and evolve, and in particular the mechanisms responsible of the decreasing/cessation of the star formation activity and the morphological transformations, are still not fully understood. In this talk I will present results that were obtained by combining the morphological structure and the stellar mass properties for galaxies in the CANDELS survey. Bulge and disk properties were analyzed to constrain the bulge-growth mechanism and also to understand the possible link with the quenching process (Dimauro et al. 2018, 2019).

05/07/19 (Friday)
12:00, Library (ESO, Vitacura) | ESO Santiago
TMT (30 minutes talk)
Talk — The Vatican Apostolic Library’s Digitization Project: the future of our past.
Dr. Giuliano Giuffrida (Vatican Apostolic Library)

## Abstract

Since its foundation on the 15th century the Vatican Library always mantained its duty to preserve and disseminate historical and cultural heritage. In this context, a project of long term digital preservation began in 2010.
Here I’ll describe the challenges we are facing and what role played the choice of the FITS file format, describing the digitization workflow put in place and the procedure adopted for the data validation.

04/07/19 (Thursday)
15:30, Urania room (ESO, Santiago) | ESO Santiago
ESO Colloquium
Talk — 4MOST a new powerful survey facility for the VISTA Telescope
Jean-François Pirard (ESO)

## Abstract

4MOST will provide to the ESO community a world-class optical spectroscopic survey facility that will make major contributions to many of the science areas. Specifically fundamental contribution can be made to the Extreme Universe (Dark Energy & Dark Matter, Black holes), Galaxy Formation & Evolution, and the Origin of Stars and Planets science cases. The unique capabilities of the 4MOST facility are enabled by its large field-of-view, high multiplex, its broad optical spectral wavelength coverage, and a dedicated telescope at a first-class astronomical site: VISTA at Paranal. The talk will present the instrument, the required modification of the telescope and some general introduction about the new operation scheme specific for this instrument.

12:00, Library (ESO, Vitacura) | ESO Santiago
ESO Thirty Minute Talks
Talk — A unifying explanation of complex frequency spectra of γ Dor, SPB and Be stars: combination frequencies and highly non-sinusoidal light curves
Donald Kurtz (Jeremiah Horrocks Institute, University of Central Lancashire)

## Abstract

There are many Slowly Pulsating B (SPB) stars and γ Dor stars in the Kepler mission data set. The light curves of these pulsating stars have been classified phenomenologically into stars with symmetric light curves and with asymmetric light curves. In the same effective temperature ranges as the γ Dor and SPB stars, there are variable stars with downward light curves that have been conjectured to be caused by spots. Among these phenomenological classes of stars, some show frequency groups' in their amplitude spectra that have not previously been understood. While it has been recognized that non-linear pulsation gives rise to combination frequencies in a Fourier description of the light curves of these stars, such combination frequencies have been considered to be only a minor constituent of the amplitude spectra. Now, we have unified the Fourier description of the light curves of these groups of stars, showing that many of them can be understood in terms of only a few base frequencies, which we attribute to g-mode pulsations, and combination frequencies, where sometimes a very large number of combination frequencies dominate the amplitude spectra. The frequency groups seen in these stars are thus tremendously simplified. We show observationally that the combination frequencies can have amplitudes greater than the base frequency amplitudes, and we show theoretically how this arises. Thus, for some γ Dor and SPB stars, combination frequencies can have the highest observed amplitudes. Among the B stars are pulsating Be stars that show emission lines in their spectra from occasional ejection of material into a circumstellar disc. Our analysis gives strong support to the understanding of these pulsating Be stars as rapidly rotating SPB stars, explained entirely by g-mode pulsations.

## June 2019

27/06/19 (Thursday)
16:00, Library (ESO, Vitacura) | ESO Santiago
ESO Colloquium
Talk — Asteroseismology: A New Keplerian Revolution
Donald Kurtz (Jeremiah Horrocks Institute, University of Central Lancashire)

## Abstract

In 1926 in the opening paragraph of his now-classic book, The Internal Constitution of the Stars, Sir Arthur Eddington lamented, “What appliance can pierce through the outer layers of a star and test the conditions within?” While he considered theory to be the proper answer to that question, there is now an observational answer: asteroseismology. We are in a time of a significant advance in our understanding of stellar astrophysics with data from the Kepler Mission. From its rich 4-year data set about 4000 exoplanet candidates have been discovered - the majority of all known. Kepler has also improved our ability to see pulsations and variability in stars by 100 to 1000 times compared with ground-based telescopes, allowing us to probe stars using asteroseismology. We are seeing as never before: heartbeat stars, novel eclipsing stars, spots, flares and magnetic cycles as in our own Sun. Astrophysics that used to be theoretical is now also observational: internal stellar rotation from core to surface; gravitational lensing in eclipsing binary stars; Doppler boosting; multiple pulsation axes; period doubling; tidal excitation in highly eccentric binary stars. Kepler data for solar-like stars are now comparable to data for the Sun seen as a star, giving us masses, radii and ages for thousands of single stars, allowing determination of their orbiting planets’ sizes, and giving new constraints on stellar evolution theory. It is now even possible to see into the cores of red giants and observe which stars are hydrogen shell-burning and which also are helium-core burning. This talk will introduce the concepts of asteroseismology and show a selection of exciting observational results from the Kepler mission. It will also show new results from TESS (Transiting Exoplanet Survey Satellite), which is in orbit and delivering data now.
12:00, Library (ESO, Vitacura) | ESO Santiago
ESO Thirty Minute Talks
Talk — The abundance discrepancy phenomenon in planetary nebulae: recent results
Jorge Garcia Rojas (Instituto de Astrofísica de Canarias, Tenerife)

## Abstract

In this talk I will focus in the latest advances that my group has reached on the study of the abundance discrepancy problem in planetary nebulae, with special emphasis in the importance of collecting deep, high-quality data of planetary nebulae taken with the most advanced instruments attached to the largest ground-based telescopes. I will present a sketch of the scenarios proposed to explain the abundance discrepancy, particularly in the largest abundance discrepancy objects that are frequently associated with close binary central stars.

26/06/19 (Wednesday)
16:00, JAO Licancabur | ESO Santiago
JAO Colloquium
Talk — Solar Eclipses, Solar Transits by Venus and Mercury, and Pluto/Ultima-Thule Occultations
Jay Pasachoff (Field Memorial Professor of Astronomy at Williams College and Chair of the IAU’s Working Group on Eclipses)

## Abstract

On August 21, 2017, a total solar eclipse's band of totality swept across the Continental United States from coast to coast for the first time in 99 years. I will show and discuss some of the the images and spectra my team has obtained at the most recent eclipses, including total eclipses in Easter Island (2010), Australia (2012), Gabon (2013), Svalbard (2015), Indonesia (2016), and the United States (2017) as well as comment on annular or partial eclipses observed elsewhere. I will discuss our observational tests underway for the comparison of models of coronal heating. I will also discuss plans for the 2 July 2019 and 14 December 2020 total eclipses that cross Chile and Argentina. My team has observing sites near La Higuera and at the Cerro Tololo Inter-American Observatory.
I will also report on our observations of transits not only of the Sun by the Moon (that is, a solar eclipse), but also across the Sun by Venus and by Mercury. I will discuss ground-based imaging and Total Solar Irradiance space measurements as well as observations of the 2012 transit of Venus with Hubble by reflection off Jupiter and directly with Cassini from Saturn, providing solar-system close-up analogues to exoplanet transits.
I will close with some discussion of our stellar-occultation observations by Pluto and other objects in the outer solar system, and their relation to the recent New Horizons flyby of Ultima Thule, a billion miles beyond Pluto.
My work on solar eclipses has recently been mainly supported by the US National Science Foundation’s Atmospheric and Geospace Sciences Division, and the Committee for Research and Exploration of the National Geographic Society. The solar-system occultation work has been supported by NASA.

Jay Pasachoff is Field Memorial Professor of Astronomy at Williams College and Chair of the International Astronomical Union’s Working Group on Eclipses. He is on sabbatical at Carnegie Observatories. The fifth edition of his textbook The Cosmos: Astronomy in the New Millennium (Pasachoff and Alex Filippenko, and a new book on the intersection of art and astronomy, Cosmos: The Art and Science of the Universe (Roberta J. M. Olson and Pasachoff), have just been published. See http://solarcorona.com
24/06/19 (Monday)
12:00, Library (ESO, Vitacura) | ESO Santiago
ESO Thirty Minute Talks
Talk — Ultra-Compact Dwarf Galaxies – Signposts of tidal disruption
Steffen Mieske (ESO)

## Abstract

I will give an update on our current understanding on the nature of Ultra-Compact Dwarf galaxies. Our recently concluded survey of massive UCDs revealed the kinematic signature of a central massive object in many UCDs, plausibly explained by a super-massive black hole in their centre.  This supports the hypothesis that those UCDs are the signposts of tidal disruption of much more massive galaxies, and that UCDs as a class may harbour a previously unaccounted for population of SMBHs. An alternative explanation for the elevated M/L ratios of UCDs is that they contain non-canonical IMFs. I will summarise the work that has been done in this field regarding formation scenarios to create such extreme IMFs, and efforts to detect signatures in the data that would support the IMF scenario.

21/06/19 (Friday)
12:00, Library (ESO, Vitacura) | ESO Santiago
TMT (30 minutes talk)
Talk — Stacking UV-selected Lyman-Break Galaxies in the ALMA Frontier Fields
Rodrigo Carvajal (PUC - Pontificia Universidad Catolica de Chile)

## Abstract

The Hubble Frontier Fields offer an exceptionally deep window into the high-redshift universe; covering a substantially larger area than the Hubble Ultra-Deep (each field around 2x2 arcmin^2) field at low magnification and probing ~1–2 mags deeper in exceptional high magnification regions. This unique parameter space, coupled with the exceptional multi-wavelength ancillary data, can allow useful insights into distant galaxy populations.
We leveraged ALMA band 6 (≈263 GHz) mosaics in the central portions of five Frontier Fields to characterize the infrared (IR) properties of UV-selected Lyman-Break Galaxies (LBGs) at redshifts of z∼2–8. We investigated individual and stacked fluxes and IR excess (IRX) values of the LBG sample as functions of stellar mass (M_star), redshift, UV luminosity and slope (beta), and lensing magnification.
We will show our detections and upper limits in the context of the IRX-M_star and IRX-beta relations, which probe at least one dex lower in stellar mass than past studies. Our upper limits (as well as their stacking) exclude substantial portions of parameter space, and are sufficiently deep in a handful of cases to create mild tension with the typically assumed attenuation and consensus relations. We will also present a smooth trend between M_star and beta, which extends to low masses and blue (low) beta values, consistent with expectations from previous works.

19/06/19 (Wednesday)
12:00, Urania room (ESO, Santiago) | ESO Santiago
ESO Thirty Minute Talks
Talk — Recent advances in the studies of magnetic fields in the pre-main-sequence Herbig Ae/Be stars
Swetlana Hubrig (Leibniz Institute for Astrophysics Potsdam (AIP))

## Abstract

The pre-main-sequence phase, where the central protostar feeds
from its surrounding planet-forming accretion disc, is
crucial for understanding how worlds like our Solar System are born.
About two dozens pre-main-sequence Herbig Ae/Be stars have been reported to hold
globally organized magnetic fields. Our analysis of their magnetic fields based on
observations obtained with HARPSpol at ESO's 3.6m telescope supports the idea
that the low detection rate of magnetic fields in these stars can be explained by the
weakness of these fields: only a few stars have magnetic fields stronger than 200G,
and half of the sample possesses magnetic fields ≤ 100G, whereas their lower mass T Tauri
counterparts possess kG magnetic fields.

13/06/19 (Thursday)
12:00, Urania room (ESO, Santiago) | ESO Santiago
TMT (30 minutes talk)
Talk — SUDARE: supernova diversity and rate evolution
Fabio Ragosta (INAF, Italy)

## Abstract

We will describe the strategy, data reduction tools and the results of the supernova search project SUDARE, which is aimed at measuring the rate of different type of supernovae in the redshift range 0.2<z<0.8.  The search was performed  at ESO VST telescope in two extragalactic fields, CDFS and COSMOS, for which ancillary data are available in the literature or in public archives. As a result of the frequent monitoring of the two selected fields, we obtained light curve and colour information for the transient sources that were used to select and classify SNe.  To measure the SN rates as a function of galaxy properties as SFR, mass, etc etc, we exploit public data and our own observations to measure the galaxy photometric redshifts and rest frame colours.
We obtained a final sample of 147 SNe  most of which are SN Ia (54%) with the remaining one being Core Collapse events, from the analysis of this sample we found that SN Ia rate per unit of mass is higher by a factor of six in the star-forming galaxies with respect to the passive galaxies identified as such both on the U − V vs V − J colour-colour diagram and for their sSFR, and the CC SN rate per unit mass is proportional to both the sSFR and the galaxy mass, confirming that the CC SN progenitors explode soon after the end of the star formation activity. The trends of the Type Ia and CC SN rates as a function of the sSFR and the galaxy mass that we observed from SUDARE data are in agreement with literature results at different redshifts suggesting that the ability of the stellar populations to produce SN events does not vary with cosmic time.

05/06/19 (Wednesday)
15:30, Urania room (ESO, Santiago) | ESO Santiago
ESO Colloquium
Talk — The Universe in a Stream: Challenges and Progress of the ALeRCE Broker
Francisco Forster (CMM, Universidad de Chile)

## Abstract

To effectively connect the astronomical follow up infrastructure with a new generation of large etendue survey telescopes such as ZTF or LSST there is a need for a new type of instrument: the astronomical alert brokers. I will review the challenges and progress of building one of these systems: the Automatic Learning for the Rapid Classification of Events (ALeRCE) astronomical alert broker. ALeRCE is a new alert annotation and classification system led by an interdisciplinary and interinstitutional group of scientists from Chile and the US. ALeRCE is focused around three scientific cases: transients, variable stars and active galactic nuclei. In this talk I will discuss some of the challenges associated to the problem of alert classification, including the ingestion, annotation, database management, training set building, distributed processing, machine learning classification and visualization, or the challenges of working in large interdisciplinary teams. I will show some results based on the real‐time ingestion and classification using the ZTF alert stream as input, as well as some of the tools available. Interested users are central to this project and are welcome to guide and/or contribute to our development efforts.

04/06/19 (Tuesday)
12:00, Library (ESO, Vitacura) | ESO Santiago
ESO Thirty Minute Talks
Talk — Galactic Planetary Nebulae with Emphasis on those that are Members of Open Star Cluster
Vasiliki Fragkou (The University of Hing Kong)

## Abstract

The study of Planetary Nebulae (PNe) provides vital clues for understanding late stage stellar evolution and stellar mass loss. Despite their significance, various issues concerning these objects remain unsolved. Interstellar extinction by dust hampers the detection of many Galactic PNe at optical wavelengths while their largely unknown distances and progenitor masses are two key parameters that hamper deeper understanding.
Identification of dust obscured PNe can be partially solved with observations at longer wavelengths where extinction effects are less serious and by multi-wavelength techniques proposed for their detection. Here, the efficacy of these methods is evaluated for identification of new Galactic PN candidates.
PNe in Galactic star clusters have distances and progenitor masses determined independently from cluster color-magnitude diagrams. Here, we study the first confirmed PN-open cluster pair (PHR1315-6555 – AL 1) identifying its central star and measuring its physical properties. We also demonstrate in detail the physical association of PN BMP J1613-5406
with Galactic open cluster NGC 6067. The PN’s progenitor mass is   ̴5.6 Mʘ. Finally, we provide preliminary details on several additional cases of possible PN-cluster associations we have uncovered.
Our new PN-open cluster associations contribute to the improvement of the initial-to-final mass relation and our multi-wavelength study suggests that a new erabegins for the identification of Galactic PNe hidden by dust.

03/06/19 (Monday)
15:30, Urania room (ESO, Santiago) | ESO Santiago
ESO Colloquium
Talk — Dual Power Law Distribution for the Initial Mass Function
Karl Heinz Hoffmann (Technische Universität Chemnitz)

## Abstract

We introduce a new dual power law (DPL) probability distribution function
for the mass distribution of stellar and substellar objects at birth, otherwise
known as the initial mass function (IMF). The model contains both
deterministic and stochastic elements, and provides a unified framework
within which to view the formation of brown dwarfs and stars resulting from
an accretion process that starts from extremely low mass seeds.
12:00, Urania room (ESO, Santiago) | ESO Santiago
ESO Thirty Minute Talks
Talk — Fun with Radiative Entropy Transfer
Christopher Essex (University of Western Ontario)

## Abstract

Photons, neutrinos, thermodynamics, and atmospheres will be looked at. There will be some weird minimum principles, and thoughts about strange generalized winds. All this in 30 minutes!

## May 2019

28/05/19 (Tuesday)
12:00, Urania room (ESO, Santiago) | ESO Santiago
ESO Thirty Minute Talks
Talk — The curious case of II Lup: plumes, spirals and obscurations
Foteini Lykou (The University of Hong Kong)

## Abstract

I will be presenting my recent work (Lykou et al. 2018) on high-angular resolution imaging on the circumstellar envelope of a peculiar C-rich AGB star, II Lup, from NACO, VISIR and ALMA observations. Our images indicate that we may have detected the origin of a spiral arm in the near-infrared, which should be related to the spiral seen by ALMA.

23/05/19 (Thursday)
12:00, Urania room (ESO, Santiago) | ESO Santiago
ESO Thirty Minute Talks
Talk — The COSMIC-DANCe project: overview and current results.
Javier Olivares (Université de Bordeaux)

## Abstract

The initial mass function is a key element in our understanding of the universe. The objective of the COSMIC-DANCe project (PI H. Bouy) is the determination of the (present-day) mass distribution of nearby (<500pc) star forming regions and open clusters. In order to derive these, we complement current surveys (i.e. Gaia and 2MASS) with archival images and our own observations. Thus, we obtain precise astrometry and photometry which allows us to probe well into the brown dwarf and planetary mass domain. We use state of the art machine learning algorithms to identify cluster members and derive their mass distribution. I will present the results of the Pleiades, IC4665, and Ruprecht 147 open clusters, together with a glimpse at our current work on Taurus, Corona Australis and Upper Scorpius star-forming regions.

22/05/19 (Wednesday)
15:30, Urania room (ESO, Santiago) | ESO Santiago
ESO Colloquium
Talk — Slow Time
Christopher Essex (University of Western Ontario)

## Abstract

Humans experience a narrow window of timescales. On timescales too short (fast time) nearly simultaneous and simultaneous become blurred. Too quick tends to be too small also: think of atoms colliding. Ultra-long timescales (slow time) reflect events that we don't see either: think geology. We are naturally biased toward happenings within our narrow window. We get distracted by faster events, get bored, or don’t live long enough to develop good intuition beyond  the slow time limit. What if we could move our window beyond it? What would it be like? Many things we are used to disappear, while other new dynamics and structures emerge. Just as the physics of “nanoscales” is different from our everyday world, so too will the physics and mathematics of “megascales” be different.  Through images, videos, and calculations we will visit worlds where people and wind disappear, water drifts like snow, and the Sun becomes sparkling arches that no human eyes will ever see.

17/05/19 (Friday)
15:30, Urania room (ESO, Santiago) | ESO Santiago
ESO Colloquium
Talk — Gods, heroes and constellations: cosmography and myths in Greek ceramics and literature
David Barrado y Navascues (Spanish Center for Astrobiology)

## Abstract

Eratosthenes of Cyrene (276-194 BCE) was one of the great scholars of the Hellenistic period. Responsible for the Library of Alexandria,
he made fundamental contributions in both Astronomy and Geography. Among the legacy he left to us is the work "Catasterisms"
(From Ancient Greekκαταστερισμός(katasterismós, “star legend”, from καταστερίζωor “to place among the stars”`
16/05/19 (Thursday)
16:00, Licancabur meeting room | ESO Santiago
JAO Colloquium
Talk — ALMA Dust Polarization Study toward Prestellar and Protostellar Sources in Orion
Satoko Takahashi (ALMA/NAOJ)

## Abstract

Great improvements in the (sub)millimeter observing sensitivity and angular resolution with ALMA enabled us to directly image the magnetic fields through the dust polarization toward star forming regions. At the same time, reported results suggest that origin of the dust polarization is not only originating from dust grains aligned in the magnetic field, but also the dust polarization can be explained by self-scattering. Dust grains aligned with the radiation field and/or gas flow are also able to produce the polarized emission. Origin of the dust polarization changes by evolutionary stage, observing wavelength, and structure size of sources. In order to observationally study the dust polarization properties, we observed seven intermediate-mass prestellar and portostellar cores located in the northern part of the Orion Molecular Cloud. We detected polarized emission toward four protostellar (Class 0 and Class I) sources, while no polarized emission was detected toward two prestellar and one Class 0 sources. Three protostellar sources show 100 au-scale elongated disk-like structures with the polarization E-vectors aligned in their minor axis. Measured polarization fractions of the three sources are within a few percent. Origin of the polarized emission can be explained by the self-scattering mechanism or alternatively toroidal wrapping of the magnetic field lines. Moreover, a bright Class 0 source showed complex substructures in the Stokes I and polarized emission. Derived polarization fraction (>10%) is significantly higher than those derived in other sources. In this talk, I will present polarization images obtained from individual sources, discuss the origin of their polarized emission, and finally make comparisons of all the sources to discuss correlations between their evolutionary stage and their polarization properties.

15/05/19 (Wednesday)
15:30, Urania room (ESO, Santiago) | ESO Santiago
ESO Colloquium
Talk — ALMA constraints on distant dusty star-forming galaxies
Franz Bauer (Pontificia Universidad Católica de Chile)

## Abstract

I will present recent efforts to detect and characterize the population of "normal" dusty star-forming galaxies (DSFGs; F850um~0.1-5 mJy) found in the Chandra Deep Field-South (ASPECS, BASIC) and cluster-lensing fields (ALMA-FFs, ALCS). In contrast to rare and extreme DSFGs, this population produces ~20-50% of the Cosmic IR background, and thus represents a major contributor to the build-up of stellar mass in massive galaxies. Robust CO-line redshifts exist for a small subset of sources, while the remainder are constrained by relatively weak photometric and FIR redshifts. I will discuss the average properties of the samples, and highlight a few intriguing/extreme outliers.

08/05/19 (Wednesday)
12:00, Urania room (ESO, Santiago) | ESO Santiago
ESO Thirty Minute Talks
Talk — Deciphering Lyman alpha emitting galaxies with integral field spectroscopy
Christian Herenz (University of Stockholm)

## Abstract

Lyman alpha emitting high-redshift galaxies offer insights into
galaxy formation processes in the young universe.  Moreover, they can
be used to address cosmological questions regarding the "Epoch of
Reionisation" and the nature of dark energy.  In my talk I will show
how integral field spectroscopy (IFS) is a viable observational
technique for such studies.  In particular, I will detail how we use
IFS data to understand Lyman alpha escape mechanisms in a sample of
nearby high-redshift analogues.  I will then show how we use the
revolutionary IFS instrument MUSE for conducting surveys of Lyman
emitting galaxies in the redshift range 3 < z < 6.  Here I will
provide an overview over the latest results from those campaigns, with
a particular focus on luminosity function studies.

07/05/19 (Tuesday)
12:00, Library (ESO, Vitacura) | ESO Santiago
TMT (30 minutes talk)
Talk — Mapping Quasar Light Echos in 3D with HI Lya Forest Tomography
Tobias Schmidt (INAF, Italy)

## Abstract

The UV radiation from bright quasars has a strong impact on the
ionization state of the surrounding intergalactic medium and therefore
causes a 'light echo' which carries detailed information about the
quasar emission properties over the last 100 Myr. I developed a novel
method to to map quasar light echoes in 3D using the IGM absorption
along many background sightlines, a technique described as Lya forest
tomography. I will present results from my feasibility study and show
that detailed constraints on quasar lifetime and obscuration properties
can be achieved with realistic observing times.

03/05/19 (Friday)
12:00, Library (ESO, Vitacura) | ESO Santiago
TMT (30 minutes talk)
Talk — Studying galaxies from UV spectroscopy
Romain Thomas (European Southern Observatory)

## Abstract

Using data from the VVDS, VUDS and VANDELS galaxy redshift surveys I will review recent results on galaxy properties and evolution.

First I will present the latest results on the intergalactic medium extinction at z>4 and show that this properties is crucial when studying galaxies at high redshift. and must be taken into account to compute galaxy properties. Then, using this prescription, I we compute the Mg UV index based on the best spectral fitting template of ∼3800 galaxies. I will show that the Mg UV index is a suitable tracer of early type galaxies at an advanced stage of evolution. Selecting galaxies with the highest Mg UV index allows to select the most massive, passive and oldest galaxies at any epoch. The formation epoch computed from the fitted age as a function of the total mass in stars supports the downsizing formation paradigm where galaxies with the highest mass formed most of their stars at an earlier epoch.

02/05/19 (Thursday)
12:00, Library (ESO, Vitacura) | ESO Santiago
ESO Thirty Minute Talks
Talk — The Puzzling Blue Dips of Black Hole Candidate Swift J1357.2-0933
John Paice (University of Southampton)

## Abstract

The Low-Mass X-ray Binary Swift J1357.2-0933 has been a curious and enigmatic black hole since its discovery in 2011. Over the course of two outbursts, it has presented a host of seemingly contradicting features - such as a high inclination, but with no eclipses by the companion star. Also of interest are a series of periodic dips, which change in frequency as outbursts occur - and which appear in the optical, but not in X-rays. We now present rapid, multiwavelength photometry using several sets of quasi-simultaneous ULTRACAM/NTT (optical), NuSTAR (X-ray), Swift/XRT (X-ray), SALT (optical) and ATCA (radio) observations taken during the decline of this source's 2017 outburst. We find: 1) that the dip frequency decreases as the outburst decays, similar to what was seen in the previous outburst, 2) that the dips produce a shape similar to that in binary systems with partial disc occultations, 3) that the source becomes significantly bluer during these dips, indicating an unusual geometry compared to other LMXB dippers, and 4) that dip superposition analysis confirms the lack of an X-ray response to the optical dips. In this talk, I will present these data, show our analysis of these unique features, and hope to garner intrigue - and perhaps even suggestions - as to the true nature of this mysterious source.

## April 2019

26/04/19 (Friday)
12:00, Urania room (ESO, Santiago) | ESO Santiago
TMT (30 minutes talk)
Talk — Infrared variability around planetesimal-eating white dwarfs
Laura Rogers (Institute of Astronomy, Cambridge University)

## Abstract

Evidence for the survival of outer planetary systems to the white dwarf
phase comes from observations of planetary material polluting the
atmospheres of white dwarfs. These observations are unique in providing
the composition of exo-planetary material. Infrared observations of dust
very close to white dwarfs reveal how planetary material arrives in the
atmospheres of white dwarfs. We expect the scattering of planetary
bodies that leads to pollution to be a stochastic process, with the
potential for variability on human timescales. Such variability has been
found for the white dwarf WDJ0959-0200 among others, where a drop in K
band flux of 20% was observed within one year. I present the results
from a large scale near-infrared monitoring campaign of ~80% of all
known dusty white dwarfs using UKIRT (WFCAM) over a baseline of 3 years.

24/04/19 (Wednesday)
12:00, Urania room (ESO, Santiago) | ESO Santiago
ESO Thirty Minute Talks
Talk — Close low-mass star/BD companions : a niche to calibrate evolutionary models
Antoine Grandjean (Grenoble)

## Abstract

Most of the current mass estimates of directly imaged planets and brown dwarfs (BD) companions rely on model
and age dependant brightness-mass relationships. Yet, these relationships still require calibration, especially at
young ages. Low mass companions and BD companions with relatively short periods are perfect to do such
calibrations as they can be observed both in Direct Imaging, radial velocity and by Hipparcos and Gaia. Thus,
dynamical masses can be derived, or constrained. I will present my work on 3 systems that are of particular interest
for such studies.
23/04/19 (Tuesday)
12:00, Urania room (ESO, Santiago) | ESO Santiago
ESO Thirty Minute Talks
Talk — Using the integral-field spectrograph MUSE to target accreting proto-planets
Sebastiaan Haffert (Leiden Observatory)

## Abstract

Newly forming proto-planets are expected to create cavities and substructures in young, gas-rich proto-planetary disks. While the planets sweep up the material in the disk they accrete it onto their surface and grow larger. Accretion usually leads to strong Halpha emission from the planet which can decrease the intrinsic contrast between the planet and it host star, making Halpha imaging a very promising approach for exoplanet detection. We used recent observations from the integral-field spectrograph MUSE to observe the young stellar system PDS 70. We detected strong H-alpha emission from two distinct locations, with the first one coinciding with the discovered planet PDS 70 b. The second emission peak was identified by us a second proto-planet in the system after processing archival data of the PDS 70 system. In this talk I will present our results and discuss them in context of the current available bservations of the system.

16/04/19 (Tuesday)
12:00, Library (ESO, Vitacura) | ESO Santiago
TMT (30 minutes talk)
Talk — A Journey Across Stellar Magnetic Activity
Enza Magaudda (Eberhard Karls Universität Tübingen)

## Abstract

The origin of stellar magnetism is still not completely understood. In this talk I'm going to present both optical high-resolution spectra of Sun-like stars and multi-wavelength observations of M type stars, with the aim of highlighting the origin of magnetism in the two classes.
The most likely origin of stellar activity in Sun-like stars is dynamo mechanism. Because of the interplay between the convective motions in the envelope and the differential rotation, the magnetic field is continuously winded and amplified.
We can observe its strength using transient event that occur in the atmosphere such as starspots, flares, and coronal mass ejection.
With high resolution spectroscopy it is possible to investigaste how the activity manifests itself. The key is observing at different wavelengths to look at different depths of the stellar atmosphere.
But what happens if we study this phenomenon on late type stars in which the structure is fully convective? We do not have the answer yet. A good way to analyze the dynamo mechanism in this structure is to study the activity as a function of the stellar rotation and see how the motion can influence the dynamo mechanism.

11/04/19 (Thursday)
12:00, Library (ESO, Vitacura) | ESO Santiago
ESO Thirty Minute Talks
Talk — RPG-LHATPRO, a precise water vapor / temperature profiler, monitoring atmospheric conditions and providing line of sight profiles for all telescopes at ESO-Paranal observatory
Thomas Rose (CEO of RPG)

## Abstract

Since 2011 the first RPG-LHATPRO microwave radiometer has been continuously operated at ESO’s VLT observatory at Paranal. The instrument is permanently scanning the sky, producing full 2D maps and conical scan – time maps of PWV, LWP (liquid water path) and IR- sky temperature (10µm, cirrus monitor). In addition, the radiometer observes temperature and humidity profiles as well as wet / dry delay and atmospheric attenuation. It also includes a scanning 10µm IR radiometer (line-of-sight observations possible) to detect thin cirrus clouds that potentially harm observations in the visible and far infrared. This information is operationally used by Paranal’s weather officer and is therefore part of the observation management. The atmospheric monitoring has been classified as operation critical.

In April 2019 a second RPG-LHATPRO was installed at Paranal observatory. Its major task is to provide line-of-sight temperature and humidity profiling along the observation directions of up to 8 telescopes. In 10 minutes repetition cycles all telescopes can be tracked. The data is used for telluric corrections in photometry.

The microwave radiometer gains its information from the atmospheric O2-line complex spectrum centered at 60 GHz (temperature profiling) and the shape of the strong water vapor line at 183.3 GHz (humidity profiling).  Observation data demonstrating the high PWV accuracy and long term stability of the instrument will be presented as well as inter-comparison data of the two collocated instruments.
10/04/19 (Wednesday)
15:30, Library (ESO, Vitacura) | ESO Santiago
ESO Colloquium
Talk — 360-degree videos: Immersive visualizations of astrophysical simulations from the Galactic Center to the Cosmic Web
Christopher Russel (PUC)

## Abstract

360-degree videos are unique movies that are rendered all around you. No matter where you look - in front, behind, left, right, up, or down - you are watching the movie, though exactly what you see depends on where you look and when. Investments driven by 360-degree cameras have made these videos as easily shareable as regular movies: via the YouTube webpage on a computer, with the YouTube app on a smartphone, or get the most immersive experience in virtual reality (VR) goggles. (Facebook’s platforms also have similar capabilities.) Given this technology, a natural application is to create 360-degree videos from 3D astrophysical simulations, thereby immersing the viewer in the simulation environment. The outreach possibility is readily apparent, and scientific applications are also sure to develop from exploring simulations in this new format.

In this talk I will discuss how to make 360-degree videos, present some tips on what I have found to work well and not so well, and then show several of my 360 videos, including a tour of the cosmic web from a large scale structure simulation, and Sgr A*'s perspective of the colliding and accreting massive-star winds in the Galactic center's inner parsec. The latter video, powered by a Chandra/NASA press release, has been viewed on YouTube ( https://youtu.be/YKzxmeABbkU ) and Facebook 1.3 million times!

Please bring your internet-connected smartphone or laptop to see the videos in their native 360-degree format during the talk, and/or stick around afterwards to see the movies in VR goggles, including the latest NASA/Chandra press release video, now with X-ray emission:
https://youtu.be/wBxW2_B9_Is .

09/04/19 (Tuesday)
12:00, Urania room (ESO, Santiago) | ESO Santiago
Special Talk
Talk — TALLER SOBRE ASTRONOMÍA PARA PERSONAS CIEGAS O CON BAJA VISIÓN
Sebastián Musso (IAU-UNESCO)

## Abstract

Propongo una actividad donde podamos repasar cómo y qué se enseña de astronomía a personas con esta condición, ver material didáctico, táctil y audible, recorrer algunas experiencias propias en mis 20 años de trabajo en esta temática.
08/04/19 (Monday)
12:00, Library (ESO, Vitacura) | ESO Santiago
ESO Thirty Minute Talks
Talk — C/2017 K2 (PANSTARRS): An Extraordinary Active Comet Beyond Uranus
Bin Yang (ESO)

## Abstract

Understanding how planetary systems formed from protoplanetary disks is one of the hottest topics in astronomy. Comets are the best-preserved relics of the formation epoch and thus play an important role in learning how our solar system formed. Long-period comet C/2017 K2 (PANSTARRS) (“K2”) is extraordinary for showing activity when at extreme heliocentric distances, out to ~26 AU. Unlike other comets, K2 is too distant and cold to be powered by the sublimation of water ice or by crystallization. No pre-perihelion comet has ever before been studied at such large heliocentric distance. K2, thus, offers us the unprecedented opportunity to examine the development of a long period comet as it warms from Oort Cloud temperatures (~10K) upon approach to the Sun. In this talk, I will first review mechanisms that can drive distant activity in comets. I will then present available observations of K2  and discuss our current understanding of the activity in K2 at the farthest distance from the Sun.

05/04/19 (Friday)
16:00, JAO Licancabur | ESO Santiago
JAO Colloquium
Talk — What the Sub-mm Variability of Embedded Protostars Tells Us about Accretion: Past, Present, and Future
Doug Johnstone (Principal Research Officer, NRC-Canada Herzberg Astronomy and Astrophysics)

## Abstract

We have undertaken a 4-year dedicated JCMT/SCUBA-2 monitoring program of eight nearby star-forming regions (Herczeg et al. 2017) to search for sub-mm brightness variations as a proxy of episodic accretion. In this talk I will discuss the novel methods used to reach a relative calibration of 2% (Mairs et al. 2017a) and present the first variable source found in the sub-mm with a periodic light curve, the Class I protostar EC 53 in Serpens Main (Yoo et al. 2017). The change in sub-mm brightness of EC 53 is interpreted as dust heating in the envelope, generated by a luminosity increase of the protostar. The sub-mm lightcurve resembles the historical K-band light curve, which varies by a factor of ∼6 with a 543 period and is interpreted as accretion variability excited by interactions between the accretion disk and a close companion. I will also discuss the results from a statistical analysis of the first eighteen months of the survey (Johnstone et al. 2018).  From these studies, we conclude that greater than 10% of the known deeply embedded protostars are found to vary in the sub-mm over year timescales.  I will close with a short discussion of other forms of variability found in the JCMT time-monitoring observations.

12:00, Urania room (ESO, Santiago) | ESO Santiago
ESO Thirty Minute Talks
Talk — Giant planets in the GAIA-TESS era
Matias Jones (ESO)

## Abstract

In this talk I will briefly review the current status of extrasolar planets,
mainly focused on the role of space mission like Kepler,
K2 and TESS in the detection of transiting systems.
I will also show the importance of accurate parallaxes provided by GAIA
for a detailed characterization of the host stars, and thus the phisycal
properties of their planetary companions.
Finally I will describe my personal contribution to the follow-up confirmation and
characterization of the first giant planets detected by the TESS mission.
04/04/19 (Thursday)
14:00, Licancabur meeting room | ESO Santiago
Meeting — An introduction to 4MOST
G. Mathys - B. Leibundgut - C. Melo (ESO)
View slides |

## Abstract

The ESO Representation Office is hosting a presentation of the future VLT instrument 4MOST to the Chilean astronomical community, with a view to helping its interested members to prepare themselves for taking the best possible advantage of the scientific opportunities opened by this new instrument.

Agenda of the activity:

14:00–14:05 Introduction (G. Mathys)
14:05–14:50 4MOST operations, surveys and policies (B. Leibundgut)
14:50–16:00 General discussion
16:00–16:15 Coffee break
16:15–17:15 Individual questions
17:15–17:20 Conclusions (C. Melo)

LeibundgutB-Apr042019.pdf

12:00, Library (ESO, Vitacura) | ESO Santiago
ESO Thirty Minute Talks
Talk — The ELT: questions and answers
Jason Spyromilio (ESO)
03/04/19 (Wednesday)
12:00, Library (ESO, Vitacura) | ESO Santiago
TMT (30 minutes talk)
Talk — 1278 days as ESO Fellow in Chile: summary of a prolific period
Jorge Lillo-Box (European Southern Observatory)

## Abstract

In this goodbye talk before I leave Chile, I will summarize the science I have been able to develop during the ESO Fellowship and I will recap on how much I've learned during my Paranal turnos. I will show how the TROY project has moved forward thanks to the freedom that the ESO fellowship provides and present other interesting results in which I've been involved during these years. I will also discuss about my experience as ESPRESSO and XSHOOTER fellow.

## March 2019

28/03/19 (Thursday)
12:00, Atenea room | ESO Santiago
TMT (30 minutes talk)
Talk — Quasars have fewer companions than normal galaxies
Minghao Yue (Steward Observatory, University of Arizona)

## Abstract

We investigate the distribution of companion galaxies around quasars using HST ACS/WFC archival images. Our master sample contains 532 quasars which have been observed by HST ACS/WFC. We search for companions around the quasars with a projected distance of 10 kpc < d < 100 kpc. A control sample of galaxies is constructed to have similar redshift distribution and stellar mass range as the quasar sample using data from HST deep fields. We find that quasars show a 3.7-sigma deficit of companions compared to control sample galaxies. Assuming that merger-triggered quasars have entered the final coalescence stage during which individual companions are no longer detectable at large separation, our result is consistent with a picture in which a significant fraction of quasars is triggered by mergers.

27/03/19 (Wednesday)
15:30, Atenea room | ESO Santiago
ESO Colloquium
Talk — Magnetic fields and activity in single red giants
Dr. Svetla Tsvetkova (Institute of Astronomy and NAO Rozhen, Bulgarian Academy of Sciences)

## Abstract

A lot of objectS throughout the entire Hertzsprung-Russell diagram host
magnetic fields. The impact of the magnetic fields on the stellar
evolution is an important one. Single late-type giants have been clearly
detected to possess weak magnetic fields in the last decade thanks to the
new generation high-resolution échelle spectropolarimeters Narval and
ESPaDOnS. Their magnetic fields vary in the interval of a few gauss up to
about 40 G measured through Zeeman signatures. It was shown that the
giants which follow the relation between the magnetic field strength and
the rotation period host an α-ω dynamo. However, the giants which possess
relatively strong magnetic fields and slow rotation (and deviate the
relation mentioned above) are probable descendants of Ap stars on the main
sequence – there are 3 such stars in our sample. Studying the Stokes I
(unpolarized) and Stokes V (circular polarization) parameters and
employing the Zeeman Doppler Imaging (ZDI) technique, we were able to
reconstruct the surface magnetic field topology for some of the giants of
our sample. The giants with dynamo operation, show complex surface
structures, while the ones, suspected of being Ap star descendants, show
clear dipolar structure.

25/03/19 (Monday)
12:00, Urania room (ESO, Santiago) | ESO Santiago
ESO Colloquium
Talk — The ATLAS All-sky Survey for Dangerous Asteroids
John Tonry (University of Hawaii)

## Abstract

Just as the entire world was first mapped in the 16th century, technology in the 21st century has opened the door to observing the entire sky all the time.  We have initiated what we think is the most cost-effective survey for near Earth asteroids and the variable sky, the "Asteroid Terrestrial-impact Last Alert System".  I will describe ATLAS, how we approach our NASA mission to find NEOs, how ATLAS fits in with other ongoing or planned surveys, some of the data products that are available now, and the many new scientific opportunities that are emerging and waiting to be exploited.

14/03/19 (Thursday)
16:00, JAO Licancabur | ESO Santiago
JAO Colloquium
Talk — Observational Planet Formation
Robin Dong (University of Victoria)

## Abstract

Planets form in gaseous protoplanetary disks surrounding newborn stars. As such, the most direct way to learn how they form from observations is to directly watch them forming in disks. In the past, this was difficult due to a lack of observational capability, and planet formation was a subject of theoretical research. Now, thanks to a fleet of new instruments with unprecedented resolving power that have come online in the past decade, we have just started to unveil features in resolved images of protoplanetary disks, such as gaps and spiral arms, that are most likely associated with embedded (unseen) planets. By comparing observations with theoretical models of planet-disk interactions, the properties of these still forming planets may be constrained. Such planets help us test planet formation models. This marks the onset of a new field: observational planet formation. I will introduce the current status of this field, highlight some of the latest developments, and discuss where this field is heading.

13/03/19 (Wednesday)
15:30, Urania room (ESO, Santiago) | ESO Santiago
ESO Colloquium
Talk — Cherenkov Telescope Array: Optical astronomy & Intensity interferometry
Dainis Dravins (Lund Observatory)

## Abstract

CTA is coming to Paranal/Armazones!  The main task of its almost 100 telescopes will be gamma-ray astronomy, but the telescopes are optical.  An unprecedented light-collecting area of some 5,000 m^2, distributed over a few square km, will enable various programs that can tolerate imperfect optics.  Such include stellar occultations by Kuiper-belt and Oort-cloud objects, and the electronic connection of many telescopes for long-baseline intensity interferometry, aiming at direct imaging of stellar surfaces.  Here, telescopes connect electronically, and the error budget relates to electronic (not optical) measures, enabling an optical equivalent of radio interferometers.

11/03/19 (Monday)
12:00, Library (ESO, Vitacura) | ESO Santiago
ESO Thirty Minute Talks
Talk — The evolution of the stellar mass - size relation of galaxy components.
Kalina Nedkova (Tufts University)

## Abstract

When trying to understand the role of bulges in the transition of galaxies from star-forming, disk-dominated systems into passive, bulge-dominated systems, one crucial piece of information is, naturally, the bulge-to-total ratio of the examined objects. Unfortunately, this is inherently difficult to measure, especially for large samples and at high redshift. Additionally, it is still somewhat under discussion whether the mass-size relation of bulges follows the same correlation as that of elliptical galaxies as a whole, which would also put constraints on the evolution scenarios leading to star formation quenching. Again, however, this is largely because making these measurements is by design difficult. While recent studies have examined this relation to higher and higher redshifts and smaller stellar masses, most of these works are still limited by modeling galaxies as one-component systems using single band imaging. By taking advantage of the Hubble Frontier Fields program imaging, some of the deepest multi-wavelength Hubble Space Telescope images in existence, and by fitting galaxy sizes in multiple bands simultaneously, we are able to separate the main galaxy components - bulge and disk - and explore the mass-size relation not just for star forming galaxies as a whole but also their bulge and disk components individually. In this talk, I will address how the recovered mass-size relations for bulges and disks line up with the established mass-size relations of early- and late-type galaxies, respectively.

05/03/19 (Tuesday)
12:00, Urania room (ESO, Santiago) | ESO Santiago
TMT (30 minutes talk)
Talk — Changing-look quasars : a challenge for the AGN unification model
Damien Hutsemekers (Liège Université)

## Abstract

Type 1 active galactic nuclei (AGNs) are characterized by both broad and narrow emission lines in their optical spectrum while type 2 AGNs only show narrow emission lines. The “unification model” suggests that type 1 and type 2 AGNs are the same objects viewed under different inclinations, the AGN core being obscured by an equatorial dusty torus in type 2 objects. A key argument in favor of the unification model was the discovery of hidden broad line regions in type 2 AGNs using spectropolarimetry. A handful of high luminosity AGNs (quasars) changing from type 1 to type 2 or vice-versa on timescales of a few years have been recently uncovered, thus challenging the unification model. To explain these spectral changes, two main scenarios have been proposed: a variation of the rate of accretion onto the supermassive black hole, or variable dust absorption due to the motion of individual clouds in a clumpy torus. Observations constraining these scenarios will be discussed, with particular emphasis on polarization measurements.

## February 2019

27/02/19 (Wednesday)
16:00, JAO Licancabur | ESO Santiago
JAO Colloquium
Talk — The production of dust in galaxies
Francisca Kemper (ESO)

## Abstract

The evolution of interstellar dust reservoirs, and the evolution of galaxies themselves go hand-in-hand, as the presence of dust alters evolutionary drivers, such as the interstellar radiation field and the star formation history, while at the same time, the dust is being formed and altered by processes taking place in galaxies. Indeed, dust can often even be used as a tracer of physical conditions. The exact mineralogical composition, the size and the shape of dust grains, are all affected by the physical conditions. Due to the more permanent nature of solids, dust grains provide a historical record of its processing history, while interstellar gas will only ever probe the present conditions.
I will discuss our recent results on the Magellanic Clouds, Local Group galaxies, the Milky Way, AGN tori, and starburst galaxies, and highlight future observational opportunities open to astronomers to continue the study of interstellar dust in galaxies.

12:00, Urania room (ESO, Santiago) | ESO Santiago
TMT (30 minutes talk)
Talk — First science with HETDEX
Maximilian Fabricius (Max Planck Institute for Extraterrestrial Physics)

## Abstract

The Hoppy-Eberly Telescope Dark Energy Experiment is a blind spectroscopic survey that will detect ~ 0.8 Million Lyman Alpha Emitting Galaxies at 1.9 < z < 3.5 to constrain models of Dark Energy via measurements of their large-scale structure. The main survey instrument VIRUS consists of 78 fiber-based Integral Field Units that feed twice as many optical spectrographs. HETDEX has started early science operations at the end of 2017 and has since been collecting data while still being commissioned. I will give a brief overview over its instrumentation and main science goals. I will show examples of the early data collected in the COSMOS field, the challenges that we face in analyzing them, and the exciting science prospects that they hold.

26/02/19 (Tuesday)
15:30, Urania room (ESO, Santiago) | ESO Santiago
TMT (30 minutes talk)
Talk — The build-up of mass and angular momentum in galaxies across morphology and environment with SAMI
Jesse Van de Sande (Sydney Institute for Astronomy)

## Abstract

Studying the build-up of mass and angular momentum in galaxies is fundamental to understanding the large variations in morphology and star formation that we see in present-day galaxies. In this talk I will highlight several key results from the SAMI Galaxy Survey, which provides two-dimensional stellar population, gas and stellar kinematic measurements for ~3000 galaxies. I will show how specific angular momentum and lambdaR (spin parameter proxy) change as a function of morphology and environment, and compare these to predictions from cosmological simulations. Furthermore, I will present recent results that link the intrinsic shape of galaxies and their stellar populations to their rotational properties.

12:00, Urania room (ESO, Santiago) | ESO Santiago
TMT (30 minutes talk)
Talk — Nuclear activity, gas flows and star formation in nearby AGNs observed with near-infrared integral-field spectroscopy
Nastaran Fazeli (Universität zu Köln)

## Abstract

The central kiloparsec of galaxies harbor critical information about a wide range of physical processes originated in different eras. Studying these regions, specially the ones with an AGN in the center, can lead to understand the evolution of galaxies. Near-infrared integral-field spectroscopy is a powerful tool tracing the distribution and dynamics of several elements (molecular and ionized gas, stars, …) that constrain complex physical mechanisms and interactions such as cold and warm gas reservoirs, inflow and outflow motions, and finally the conditions and impact of star formation in galactic centers. I will show recent results that we achieved using the NIR-IFS SINFONI at the ESO-VLT. In particular, I will show the NIR data of a small sample of AGN/starburst host galaxies from the NUGA sample that were also observed with ALMA in the sub-mm. All of them show circumnuclear star formation rings. I will also discuss traces of inflow and outflow motions in the gaseous kinematics.

25/02/19 (Monday)
12:00, Library (ESO, Vitacura) | ESO Santiago
TMT (30 minutes talk)
Talk — Disentangling the formation of dwarf galaxy nuclei with MUSE
Evelyn Johnston (Pontificia Universidad Catolica de Chile)

## Abstract

Central star clusters, or nuclei, are seen in many dwarf galaxies, and become more frequent in higher mass dwarfs. Since higher mass dwarf galaxies are thought to have been built up through accretion and minor mergers with neighbouring galaxies, it’s likely that these nuclei are signatures of such events. For example, they could be the stripped remnants of an accreted galaxy, or they could have been formed internally due to tidal disruption from a passing galaxy. These scenarios can be distinguished through studies of the star-formation histories of the nuclei and the host galaxy.  However, the relative faintness of these nuclei mean any spectra extracted from the region of the nuclei for this analysis would be heavily contaminated by the light of the host galaxy. Until now.

In this talk, I will present BUDDI (Bulge-Disk Decomposition of IFU data) as a new way to cleanly model and isolate the spectra of the nuclei and the host galaxy, allowing us to study their star-formation histories independently for the first time. We have successfully applied this technique to a sample of dwarf galaxies in the Fornax Cluster, and I will discuss our preliminary results and reveal whether they reveal the nuclei to be of internal or external origin to the host galaxies.

20/02/19 (Wednesday)
15:30, Urania room (ESO, Santiago) | ESO Santiago
ESO Colloquium
Talk — Obscured Galactic Nuclei
Eduardo González Alfonso (Universidad de Alcala, Spain)

## Abstract

Obscured Galactic Nuclei are compact nuclear regions of galaxies with very high column densities
(N_H>~10^24 cm-2) and luminosity surface brightness (>~5x10^13 Lsun/pc^2), which are mainly found in
(Ultra-)Luminous Infrared Galaxies. The physical properties of these regions as inferred from spectroscopic
observations of molecular species, from the far-infrared to millimeter wavelengths, will be reviewed.
Specifically, I will make emphasis on far-infrared observations of OGNs as carried out by Herschel/PACS
and SPIRE, which show extreme excitation of OH, H2O, OH+, and other species, and high velocity outflows
(~1000 km/s) in OH.
13/02/19 (Wednesday)
15:30, Urania room (ESO, Santiago) | ESO Santiago
ESO Colloquium
Talk — Radial Velocities and Wavelengths Shifts - Stellar Spectra and Exoplanet Detection
Dainis Dravins (Lund Observatory)

## Abstract

A major challenge lies in finding exoplanets that are “true” Earth-analogs. Limitations in radial-velocity detection seem to be less set by instrumentation than by the dynamics of stellar atmospheres: spectral lines become asymmetric and their wavelength “flickers”.  Line profiles can now be computed from 3-dimensional hydrodynamic stellar atmospheric models, revealing patterns of wavelength displacements across stellar disks.  Previously, such models could be tested only on the spatially resolved Sun but this is now feasible also for other stars, exploiting exoplanet transits.  Differential spectroscopy between various transit phases provide spectra of small stellar surface segments temporarily hidden behind the planet.  The very high S/N required can be reached after averaging many similar absorption lines, enabling retrieval of photospheric line profiles across spatially resolved stellar disks.  Additional bright host stars with large transiting planets will likely be discovered by ongoing surveys, offering suitable targets for testing hydrodynamic models with calibrations of stellar wavelength flickering.
12/02/19 (Tuesday)
12:00, Urania room (ESO, Santiago) | ESO Santiago
TMT (30 minutes talk)
Talk — Dissecting the High-redshift Interstellar Medium
Jens-Kristian Krogager (Institut Astrophysique de Paris)

## Abstract

The use of absorption techniques toward distant, bright objects offers a powerful
method for studying the high-redshift interstellar medium. These high-redshift
absorbers are typically identified via their characteristic neutral hydrogen absorption
from Lyman-α, the so-called Damped Lyman-α absorbers (DLAs).
The study of DLAs has shown that the gas probed in absorption consists of multiple

phases; however, the average DLA predominantly traces warm (T~1000 K) gas.
In order to directly trace the cold, neutral gas, out of which stars form, we have employed
a targeted search for neutral carbon and H2. In this talk I will present a particular case
where we serendipitously identified a lensed quasar where both images of the quasar
pass through a foreground galaxy allowing us to characterize the cold ISM at z~2
in unprecedented detail.
07/02/19 (Thursday)
12:00, Urania room (ESO, Santiago) | ESO Santiago
TMT (30 minutes talk)
Talk — Probing the evolution of neutral gas reservoirs over 12 Gyr with the XQ-100 survey
Trystyn Berg (European Southern Observatory)

## Abstract

Neutral gas reservoirs play a critical role in building galaxies across cosmic time. Probing these reservoirs in a consistent, blind manner over such a large range of cosmic time is currently only feasible with the use of intervening absorbing systems imprinted ontop of quasar spectra. Damped Lyman alpha systems (DLAs) are the strongest HI absorbers found along quasar sightlines, and contain the bulk of neutral gas across cosmic time. As such, DLAs are excellent tracers of how the Universe consumes and pollutes its gaseous reservoirs. The XQ-100 survey -- 100 quasars at redshifts 3.5 to 5 observed with X-Shooter -- provides an unprecedented sample of blind, high-redshift absorption line systems with simultaneous coverage of metal absorption lines. In this talk, I will highlight the recent results of the XQ-100 DLA  and subDLA surveys to quantify the evolution of HI reservoirs, as well as constrain the role DLAs play in the chemical makeup of the Universe. In particular I will focus on why metal-blind surveys are required for characterizing the cosmic density of HI in the Universe, and what the intrinsic [Zn/Fe] ratio measured in DLAs can tell us about the nature of the host galaxies.

05/02/19 (Tuesday)
12:00, Library (ESO, Vitacura) | ESO Santiago
ESO Thirty Minute Talks
Talk — News and Updates from the ESO Library
Uta Grothkopf (ESO)

## Abstract

During this TMT, we will inform you about latest News and Updates from the ESO Library and the world of scientific publishing. We will start our tour with background information about the Library’s evolution into the ESO Library and Information Centre, followed by the most recent statistics of ESO data papers derived from the Telescope Bibliography (telbib) database. We will then report about current trends in publishing and scholarly communication, with a special focus on Open Access publishing, and a discussion of your own use of published journal articles.

04/02/19 (Monday)
12:00, Urania room (ESO, Santiago) | ESO Santiago
TMT (30 minutes talk)
Talk — Towards Understanding the Origin and Evolution of Ultra-Diffuse Galaxies
Remco van der Burg (European Southern Observatory)

## Abstract

Recent observations of Ultra-Diffuse Galaxies (UDGs, which have the luminosities of dwarfs but sizes of giant galaxies) have picked up a lot of attention by the community. The origin of these galaxies remains unclear; they are routinely found in clusters while one would naively expect them to be easily disrupted by tidal interactions in such over-dense environments. Several formation scenarios have been proposed for UDGs, but these make a wide range of different testable observational predictions. I’ll summarise recent results in this field, focussing on two key observables that have the potential to differentiate between the proposed models, namely 1) a measurement of their abundance in lower-mass haloes using data from the GAMA and ESO VST-KiDS surveys and 2) a measurement of their total masses. For the latter I will describe a measurement of their average (sub)halo masses using weak gravitational lensing, but also discuss some intriguing individual galaxies such as the galaxy NGC 1052-DF2 of which we recently studied the kinematics with VLT/MUSE.

## January 2019

31/01/19 (Thursday)
16:00, Urania room (ESO, Santiago) | ESO Santiago
JAO Colloquium
Talk — Characterizing the formation mechanisms of protostellar disks: observations and models
Anaëlle Maury (CEA-Saclay)

## Abstract

Understanding the first steps in the formation of stars, protoplanetary disks, and ultimately planets, is a great unsolved problem of modern astrophysics. Observationally, the key to constraining theoretical models of disk formation lies in high-resolution studies of the youngest protostars.  I will present our IRAM/PdBI observations and modeling of the millimeter dust continuum emission in a sample of young protostars, and discuss our findings that most young protostellar disks (>75%) are only found at very small radii <60 au. I will also present our ALMA observations of the molecular line emission in a very young solar-type protostar suggesting a disk is currently forming in counter-rotation with respect to the protostellar core rotation, and discuss potential scenarii to understand this oddity. Finally, I will show our SMA and ALMA observations of the magnetic field topology at scales 50--5000 au, in a sample of young protostars.  I will compare these observed properties of the youngest protostars to synthetic observations of the typical outcome of MHD models for protostellar collapse. I will argue that our observations of small disks, counter-rotating disks and organized magnetic fields in the youngest solar-type star-forming cores question the established paradigm of disk formation as a simple consequence of angular momentum conservation during the main accretion phase: they instead highlight the need to investigate magnetized models of protostellar collapse in order to unveil the mechanisms responsible for protostellar disk properties.

30/01/19 (Wednesday)
15:30, Urania room (ESO, Santiago) | ESO Santiago
ESO Colloquium
Talk — The Thermal Response of Asteroid Surfaces
Stephen Lowry (University of Kent)

## Abstract

The (YORP) effect [1] is a torque due to incident solar radiation and the subsequent recoil effect from the anisotropic emission of thermal photons on small bodies in the solar system. The YORP effect can: change rotation rates and spin-axis orientations over relatively short time-scales; modify orbits (semi-major axis drift from the related Yarkovsky effect depends on the obliquity) and thus plays a key role in replenishment of the near-Earth asteroid (NEA) population; cause regolith mobility and resurfacing as spin rates increase; form binary asteroids through equatorial mass loss and re-aggregation; and cause catastrophic disruption. When we began our systematic monitoring programme in 2010, the YORP effect had only been detected for three asteroids [3-5] with a marginal detection following in 2012 [6]. That has now increased to six [7-8]. All detections so far are in the spin-up sense, and theoretical studies are making progress in explaining this observation [9]. However, a much larger statistical sample is required to robustly test this theory. We are conducting an observational programme of a sample of NEAs to detect YORP-induced rotational accelerations. For this we use optical photometry from a range of small to medium size telescopes. This is supplemented by thermal-IR observations and thermophysical modelling to ascertain expected YORP strengths for comparison with observations. For selected objects, we use radar data to determine shape models. We will present our latest results and progress on YORP detections/upper limits for a subset of NEAs from our programme, which include: (1917) Cuyo, (8567) 1996 HW1, (85990) 1999 JV6, (6053) 1993 BW3, and (29075) 1950 DA.

[1] Rubincam (2000). Icarus 148, 2. [2] Lowry et al. (2007). Science 316, 272. [3] Taylor et al. (2007). Science 316, 274. [4] Kaasalainen et al. (2007). Nature 446, 420. [5] Durech et al. (2008). A&A 489, L25. [6] Durech et al (2012). A&A 547, A10. [7] Lowry et al. (2014). A&A 562, A48. [8] Durech et al. (2018), A&A 609, A86. [9] Golubov, et al. (2014). ApJ 794, 22.

28/01/19 (Monday)
12:00, Library (ESO, Vitacura) | ESO Santiago
TMT (30 minutes talk)
Talk — Constraining the lithium enrichment mechanism in giants
Claudia Aguilera Gomez (UNAB)

## Abstract

Lithium is a light element, easily destroyed in stellar interiors. As such it is often used as a proxy of complex processes affecting stars. The existence of a small number of lithium-enriched giants challenges our current understanding of post-main sequence evolution. By identifying the enrichment mechanism in giants, we could shed light on non-canonical mass-dependent processes such as planet engulfment and extra-mixing. In this talk, I will discuss the importance of mass and exact evolutionary stage in understanding the lithium abundance pattern of giants and classifying the unusual stars, a necessary step to find the lithium-enrichment mechanism. I will present samples of stars where masses and metallicities can be measured, and where possible candidates of planetary accretion are identified based on their lithium abundances. Finally, I will discuss other observable signatures that are used to differentiate enhancement mechanisms, focusing on the abundance of lithium-6. The absence of this isotope on lithium-rich giants has been used against the planet accretion scenario. However, using models of planet engulfment, I will show that lithium-6 should not be used to distinguish between mechanisms in metal-rich stars.

25/01/19 (Friday)
12:00, Library (ESO, Vitacura) | ESO Santiago
TMT (30 minutes talk)
Talk — Orbits and Chemical Abundances in the Milky Way with Gaia DR2

## Abstract

Present and recent sky surveys have advanced in the effort of studying the Milky Way, making volume complete samples in both position and velocity space. In this work, the aim is to explore to which extent stars with very similar abundances are on similar or different orbits, which could give us hints on the effects of radial migration in the disc of the Milky Way. In order to do this, we need to have sizeable samples with good abundances (from a spectroscopic survey such as APOGEE or LAMOST), good distances (parallax or photometric) and proper motions (from Gaia). Here we present our probabilistic approach to model spectroscopic information that we applied to obtain improved spectrophotometric distances (with errors less then 6%) for main sequence stars in the LAMOST DR5 x Gaia crossmatch.
We explicitly account for the individual parallax uncertainties in the model building and fully incorporate the binarity of main sequence stars. For the fainter and more distant stars of most current spectroscopic surveys, an approach such as the one presented in this work delivers better distances than Gaia Data Release 2.  With these improved distances we then explore the orbital actions and the chemical information from all the main sequence stars in the LAMOST sample.

24/01/19 (Thursday)
16:00, Urania room (ESO, Santiago) | ESO Santiago
JAO Colloquium
Talk — Star formation in the GGD 27 nebula: disks around low and high mass YSOs
Josep Miquel Girart ((CSIC-IEEC))

## Abstract

GGD 27 is an optical nebula that harbors one of the most spectacular radio jets (associated with HH 80-81) powered by a young stellar object (YSO).  The HH 80-81 radio jet represents a unique case where the basic ingredients showing that high-mass protostars form through an accreting disk with a magnetic field are present: a magnetized highly collimated jet; a disk perpendicular to the jet; and possible rotating motions of the molecular gas around the massive protostar. ALMA full-polarization observations with 45 milliarcsecond resolution have well resolved the disk, and we have detected a polarization pattern that is suggestive of scattering in an optically thick disk. The ALMA data have been combined with irradiated accretion disk models, allowing us to unveil the disk and stellar mass, the accretion rate, the disk kinematical behavior, and the relevance of the magnetic fields.  These observations have also revealed a population of low mass disks around the massive protostar. We compare the general disk properties in this region with other star-forming regions. Finally, we will present an updated of the distance of GGD 27 using GAIA and near-IR data.

12:00, Library (ESO, Vitacura) | ESO Santiago
TMT (30 minutes talk)
Talk — Optical and X-ray modeling of the magnetic cataclysmic variable EV UMa
Karleyne Silva (ESO)

## Abstract

Magnetically driven accretion in white dwarfs (WDs)  provide a unique understanding of highly magnetized environments. Polars, a subclass of cataclysmic variables, have accretion columns formed when the  magnetic WD channels the partially ionized outer atmosphere from a  red-dwarf star towards the WD’s surface via Roche lobe overflow.

The accretion column emission dominates a wide wavelength range: from X-ray  to the IR domain. The optical and IR emission is mainly produced by
cyclotron emission,  resulting in high degrees of polarization, typically  up to 20%, while the X-ray emission is mainly produced by free-free emission from the heated material.

Here I present the results of broadband optical polarimetry models of the polar EV UMa from which important physical parameters are derived: the electronic
density and temperature along the  accretion column, the magnetic field and the overall geometry of the emitting region. Additionally, X-ray simultaneous modeling  was performed, and a scenario that can explain both data set is presented.
23/01/19 (Wednesday)
15:30, Urania room (ESO, Santiago) | ESO Santiago
ESO Colloquium
Talk — The metallicity abundances of discs across time
Patricia Tissera (Universidad Andres Bello - Chile)

## Abstract

Understanding the evolution of chemical abundances in galaxies provides crucial information to study how galaxies formed and evolved.
In particular, metallicity gradients have been largely studied but the important contributions from surveys such as CALIFA and MaNGA open the
possibility to gain further inside.
I will  present results of the analysis of the oxygen abundance gradients (S(O/H)) in star-forming regions in the disc components of
simulated galaxies identified from the EAGLE simulations. The simulated database is composed of 500 galaxies in different environments.
In this work, we study the metallicity gradients of the disc components a function of stellar mass, galaxy size, galaxy morphology, star formation activity and environment.
I will aso present results on the evolution of the metallicity gradients from  z<2.
14/01/19 (Monday)
12:00, Library (ESO, Vitacura) | ESO Santiago
TMT (30 minutes talk)
Talk — Preliminary analysis of comets 46P/Wirtanen and 66P/du Toit

## Abstract

Comets are among the most primitive bodies of the Solar System. They are a unique opportunity to study the primitive matter in the origin of the solar system, material that has been stored in deep freeze for 4.6 billion years. In this talk, I’m going to present the preliminary results of the study of two Jupiter-family comets 46P and 66P observed in 2018. 46P is the comet of the year for the community, as it did an unusually close approach to the Earth in December, just at 30x the distance of the moon. This allowed us to observe this comet in great detail with ground-based telescopes. I’m going to present the first results that we obtained with VLTs instruments (MUSE, UVES, and ESPRESSO) as well as the photometric and imaging survey with the TRAPPIST telescopes. For comet 66P, which has a high probability to come from the Main Belt, I will present the medium-resolution and high-resolution spectra that we obtained with X-shooter and UVES/VLT instruments. In addition, I will show also the photometric and imaging result from TRAPPIST-South telescope.

10/01/19 (Thursday)
16:00, Licancabur meeting room | ESO Santiago
JAO Colloquium
Talk — Imaging of the Thermal SZ Effect with ALMA
Tony Mroczkowski (ESO)

## Abstract

The Sunyaev-Zeldovich (SZ) effect has proven to be a powerful tool for studying large scale structure, and can be measured from the ground using mm/submm-wave instruments. Interferometers with many elements — such as ALMA — have excellent sensitivity but are be non-ideal for imaging signals spatially extended beyond scales recovered by the shortest antenna spacings.  In order to mitigate these missing flux effects, we supplement the ALMA data with lower resolution data from single-dish, large field of view telescopes like Planck and the 10-meter Caltech Submm Telescope.   After introducing the SZ effects (outlined in the review I led, http://adsabs.harvard.edu/abs/2018arXiv181102310M), I will discuss the joint analysis of single-dish and interferometric observations of the SZ effect from the galaxy cluster RX J1347.5-1145, which we recently reported on in L. Di Mascolo et al, submitted (http://adsabs.harvard.edu/abs/2018arXiv181201034D).  These tools use a Monte Carlo Markov Chain framework and the Galario package to improve computational speed.  In the case of RXJ1347.5, we find that a single ellipsoidal profile provides a good description of the thermal SZ signal. I will also discuss some recent results on measurements of the kinematic SZ effect in a small sample of clusters with deep Bolocam, AzTEC, and Herschel measurements (Sayers et al, submitted; http://adsabs.harvard.edu/abs/2018arXiv181206926S) .  Multi-frequency coverage is crucial for constraining the contamination from the dusty galaxies that comprise the cosmic infrared background (CIB).  And finally, I will motivate and encourage community participation in effort to construct a 50-meter telescope operating at mm/submm wavelengths.  This facility will strongly complement ALMA, vastly improving our ability to recover large scales and offering mapping speeds some 6 orders of magnitude than ALMA currently can.

12:00, Urania room (ESO, Santiago) | ESO Santiago
TMT (30 minutes talk)
Talk — Storms or systematics? The search for atmospheric variability in hot Jupiters
Matthew Hooton (Queen’s University Belfast)

## Abstract

The detection of the thermal emission from exoplanets during their secondary eclipses has established itself as an important tool for studying exoplanet atmospheres, with over a hundred published results to date. Making this measurement over a range of wavelengths allows models of their emission spectra to be constructed, which alludes to atmospheric features such as chemical composition, thermal structure and circulation efficiency. Interestingly, repeat observations of secondary eclipses routinely yield depths that significantly disagree. Without understanding the source of these disagreements, which could arise due to systematic errors or genuine atmospheric variability in the exoplanets themselves, it is difficult to reliably constrain the atmospheric properties of these exoplanets. I will present results from the QUB secondary eclipse campaign, which utilises ground-based telescopes to observe secondary eclipses at wavelengths not typically explored in the related literature. I will describe our past and future observations of WASP-12b, a hot Jupiter with a 10-year history of confounding observers and theorists, as well as our initial atmospheric categorisation of the newly-discovered KELT-16b. Finally, I will present our ultraviolet secondary eclipse observation of KELT-9b—the hottest known exoplanet.

09/01/19 (Wednesday)
16:00, Licancabur meeting room | ESO Santiago
JAO Colloquium
Talk — The Role of Environment in Shaping Molecular Cloud Properties
Christopher Faesi (Max Planck Institute for Astronomy)

## Abstract

Giant Molecular Clouds (GMCs) are the cradles of stellar birth across the Universe. GMCs in the Milky Way exhibit remarkable uniformity in their physical structure, while recent observations of nearby galaxies have suggested that GMC properties vary with environment. To further explore the role of environment on GMCs, I have led a series of high-resolution, high-sensitivity investigations into molecular gas and star formation in NGC 300, a nearby spiral galaxy that at a distance of 2 Mpc provides an ideal laboratory for resolved GMC studies and comparison to the Milky Way and other galaxies. In this talk, I will describe the results of our CO(2-1) ALMA study in which we achieve 10 pc and 1 km/s resolution, fully resolving GMC scales and detecting 250 clouds at high signal-to-noise. I will show that despite large differences between global properties of the Milky Way and NGC 300, the GMC populations in these galaxies are remarkably similar, having the same Larson scaling relations and a similar mass spectrum. I will show that galaxy disk midplane pressure may explain observed differences in GMC properties in other galaxies such as M51, as well as in more extreme physical environments such as the Galactic Center. I will conclude by showing first results from the PHANGS (Physics at High Angular resolution in Nearby Galaxies) project in which we are using ALMA observations to resolve GMC scales across the disks of 70 nearby spiral galaxies. These follow-up studies are confirming the central role of pressure in setting GMC properties in spiral galaxies across the star-forming main sequence.

12:00, Urania room (ESO, Santiago) | ESO Santiago
TMT (30 minutes talk)
Talk — BEBOP: Binaries Escorted By Orbiting Planets
Amaury Triaud (University of Birmingham)

## Abstract

BEBOP is a new radial velocity survey on the HARPS and SOPHIE spectrographs whose goal is to identify circumbinary planets and measure their properties. This mysterious population is hard to understand. Theoretical work informs us they should be very rare, yet, early measurements are consistent with a population that is as frequent as planets orbiting single stars. In this talk I will describe the reasons behind our survey, and show some early results.

08/01/19 (Tuesday)
12:00, Urania room (ESO, Santiago) | ESO Santiago
TMT (30 minutes talk)
Talk — The chemical evolution carousel of spiral galaxies: a 3D view of ISM metallicity with PHANGS-MUSE and TYPHOON
I-Ting Ho (MPIA Heidelberg)

## Abstract

The spatial distribution of the interstellar medium oxygen abundance is the key to understanding how efficiently metals synthesized in massive stars can be redistributed across a galaxy. One way to understand how efficient ISM mixing  occurs on orbital timescale is to probe chemical inhomogeneity in the azimuthal direction. Despite decades of studies, evidence of the presence of azimuthal variations of chemical abundances remains circumstantial. In this talk, I will present some of the highest spatial resolution 3D spectroscopic data collected by the PHANGS collaboration with MUSE and the TYPHOON Program with the du Pont telescope. These high quality data begin to approach a critical spatial scale of typical giant molecular cloud and HII region (50 to100 pc), allowing us to study the ISM chemistry and star formation in unprecedented details. I will show compelling evidence that the ISM oxygen abundance changes systematically in the azimuthal direction. The abundance variations spatially correlate with the spiral structures and are imprinted on negative radial gradients. I will place the observations in the framework of a simple chemical evolution model and demonstrate that the variations could be driven by a combination of environmentally dependent mixing time and star formation density. I will end the talk by discussing future prospects of using the on-going MUSE and ALMA large programs by the PHANGS collaboration to advance our understanding of chemical abundances and mixing on sub-kiloparsec scale.

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