ESO Santiago Science Colloquia and Seminars 2012

December 2012

 

4.12.12 (Tuesday)
12:00
"Scalelengths of Disc Galaxies"
Kambiz FATHI (Stockholm University, Sweden)
Abstract
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"Scalelengths of Disc Galaxies"

Kambiz FATHI (Stockholm University, Sweden)

Abstract

I will present exponential disc scalelengths for ~700 galaxies with spectroscopic redshifts out to redshift 5.8 based on the deepest Hubble Space Telescope archival data. The results are compared with our previous measurements based on 30 000 nearby galaxies from the SDSS. Our results confirm the presence of a dominating exponential component in galaxies out to redshift 5.8 and at the highest redshifts, the disc scalelength for the brightest galaxies with absolute magnitude between -24 and -22 is up to a factor of 8 smaller compared to that in the local Universe. This observed scalelength decrease is significantly greater than the value predicted by a cosmological picture in which baryonic disc scalelength scales with the virial radius of the dark matter halo.
10.12.12 (Monday)
12:00
"A Cepheid Distance to the Coma Cluster of Galaxies"
Michael GREGG (Department of Physics, University of California at Davis, USA)
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"A Cepheid Distance to the Coma Cluster of Galaxies"

Michael GREGG (Department of Physics, University of California at Davis, USA)

Abstract

We have used the Hubble Space Telescope cameras ACS and WFC3 to image the largest spiral galaxy in the core of the Coma cluster over twelve epochs spanning more than three months. The goal is to detect and phase Cepheid variables to obtain a distance to Coma accurate to 5%. A direct application of this canonical primary distance indicator at 100 Mpc will measure the far-field Hubble constant free of many of the systematic uncertainties which beset current determinations relying on secondary indicators. Establishing the far-field Hubble constant with Cepheids provides one of the strongest links in the extragalactic distance scale and will robustly calibrate the fiducial fundamental plane of elliptical galaxies and type Ia supernovae.
11.12.12 (Tuesday)
12:00
"Homogeneous SDSS photometry for the Galactic Globular Cluster System"
Joachim VANDERBEKE (ESO, Chile)
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"Homogeneous SDSS photometry for the Galactic Globular Cluster System"

Joachim VANDERBEKE (ESO, Chile)

Abstract

We have collected imaging data in the SDSS filters (griz) for the bulk of the Galactic globular cluster system using the CTIO 0.9m telescope. One of the main goals of the project is obtaining color-metallicity relations (CMR) based on the SDSS filters. These relations are useful for extragalactic studies and the first results on the CMR will be presented. Moreover, I will discuss the different techniques we applied to obtain clean magnitudes (including wide-field CMDs, proper motions and King profile fitting) and how we deal with non-member contamination.
12.12.12 (Wednesday)
16:00
"The Javalambre Astrophysical Observatory: The new Facility for Wide Field Surveys in Spain "
Alessandro EDEROCLITE (Centro de Estudios de Física del Cosmos de Aragón, Spain)
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"The Javalambre Astrophysical Observatory: The new Facility for Wide Field Surveys in Spain "

Alessandro EDEROCLITE (Centro de Estudios de Física del Cosmos de Aragón, Spain)

Abstract

Located in the province of Teruel, the Javalambre Astrophysical Observatory is a brand new facility completely dedicated to wide field surveys. The observatory hosts two telescopes: the Javalambre Auxiliary Survey Telescope (an 80cm telescope with a 2sq.deg. field of view, currently being commissioned) and the Javalambre Survey Telescope (a 250cm telescope with 3.5sq.deg. field of view). I will review the status of the observatory, the telescopes and the instrumentation. I will also give an overview of the scientific projects which are expected to be carried out with this instrumentation.
13.12.12 (Thursday)
12:00
"Unveiling new stellar-mass Galactic black holes"
Jesus CORRAL-SANTANA (IAC)
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"Unveiling new stellar-mass Galactic black holes"

Jesus CORRAL-SANTANA (IAC)

Abstract

It is believed that there are ~10^9 black holes in the Galaxy. However, only those in binary systems are easily detectable. X-ray transients are binary systems composed by a 'normal' star which is transferring mass to a compact object (either a black hole or a neutron star) through Roche lobe overflow. These systems show sporadic outburst episodes and long quiescence states, being the ideal systems to search for black holes. Different studies predict a Galactic population of ~10^4 X-ray transients, however, there are only 18 stellar-mass black holes dynamically confirmed and other 37 black hole candidates pending for confirmation, all of them discovered through outburst episodes. In this talk I present the latest black holes dynamically confirmed: - XTE J1859+226, the first black hole confirmed with data taken with the 10.4 m Gran Telescopio Canarias. - Swift J1357.2-0933, the first black hole seen at a large inclination. It has allowed us to trace for the first time the movement of an expansion wave in the accretion disc which is obscuring the black hole. I will also present a novel technique, using colour-colour diagrams developed with the filters of the IPHAS and UVEX surveys, to unveil black holes in quiescence (which have been proved impossible to date) to increase the current sample of Galactic black holes.
18.12.12 (Tuesday)
12:00
"Compact Radio Sources and Methanol Maser Kinematics around Massive Young Stars"
Adam AVISON (Jodrell Bank Centre for Astrophysics, Univ. of Manchester, UK)
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"Compact Radio Sources and Methanol Maser Kinematics around Massive Young Stars"

Adam AVISON (Jodrell Bank Centre for Astrophysics, Univ. of Manchester, UK)

Abstract

I will present the results of 8.64 GHz continuum observations made toward class II CH3OH masers in regions of massive star formation. These observations were conducted at the Australia Telescope Compact Array (ATCA). The target sources in our sample are 6.7GHz maser sources newly discovered during Methanol Multibeam Survey. The investigation of these data for potential evolutionary traits both morphological i.e. size and maser-continuum separation from the radio data, and from infrared association for these continuum sources will be discussed. I will then introduce a new project to investigate the potential extraction of kinematic information from the masers targeted during the MMB ATCA observations and the comparison of these kinematic data to disk/ring models.
20.12.12 (Thursday)
12:00
"Searching for the most primitive stars with X-Shooter and UVES"
Luca SBORDONE (Heidelberg University)
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"Searching for the most primitive stars with X-Shooter and UVES"

Luca SBORDONE (Heidelberg University)

Abstract

The least chemically evolved stars in the Milky Way represent arguably the most effective record of the initial phases of the assembly of our Galaxy. Their chemical composition bears the imprint of the very first nucleosynthesis events in the Universe, and of the environmental conditions in which the first star formation episodes took place. At the same time, such objects are extremely rare and difficult to identify and analyze. In this talk, I will report on the current status on an ongoing project to identify and study extremely metal poor dwarf stars in the Milky Way Halo by means of UVES and X-Shooter, starting from its initial GTO observations, leading to the discovery of the most metal-deficient star known to date (SDSS J102915+172927), and prosecuting now in the ongoing Large Program TOPoS, of which I will present the first results.

November 2012

 

12.11.12 (Monday)
12:00
"Metal rich, barium stars"
Joao Victor SILVA (Observatorio Nacional, Brazil)
Abstract
13.11.12 (Tuesday)
12:00
"Planet validation: a new era in extrasolar planet science"
Rodrigo DIAZ (Laboratoire d'Astrophysique de Marseille)
Abstract
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"Planet validation: a new era in extrasolar planet science"

Rodrigo DIAZ (Laboratoire d'Astrophysique de Marseille)

Abstract

Transiting extrasolar planets provide a wealth of information about their interiors, their atmospheres, and the architecture of multiple systems. To confirm transit candidates issued from large-area surveys like SuperWASP, CoRoT or Kepler, a measurement of the mass of the transiting object is usually required. Traditionally, this is done via radial velocity measurements. However, with the advent of CoRoT and Kepler, and their uninterrupted high-precision, space-based photometry, transiting candidates of sizes comparable to that of the Earth have been discovered. Confirmation of these objects via radial velocity measurements is out of reach of current instrumentation, due mainly to the faintness of the targets of these surveys and the small reflex motion expected to be produced by the transiting object. In this talk, I will describe how the exoplanet community is trying to circumvent this problem via the technique known as "planet validation". I will go through the perils, joys, and woes of sailing in these mostly uncharted waters, and will finally present PASTIS, a new tool for planet validation developed in Marseille. PASTIS should provide independent confirmation of the Kepler smallest planets, and pave the way for rigorous validation of the hundreds of small-size planet candidates detected to date.
14.11.12 (Wednesday)
10:00
"Quasar Absorption Lines" (Lecture 1)
Sebastian LOPEZ (Universidad de Chile)
Abstract
14.11.12 (Wednesday)
12:00
"The Emerald Planet: How plants changed Earth’s atmosphere"
(Video connection to the ESO/Garching Auditorium)

David BEERLING (University of Sheffield, UK)
Abstract
16.11.12 (Friday)
12:00
"Ecology, evolution and society"
David VELIZ (Universidad de Chile)
Abstract
19.11.12 (Monday)
12:00
"Canis Major overdensity and Monoceros ring explained in terms of pure Milky Way structure"
Martin LOPEZ CORREDOIRA (IAC)
Abstract
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"Canis Major overdensity and Monoceros ring explained in terms of pure Milky Way structure"

Martin LOPEZ CORREDOIRA (IAC)

Abstract

Some authors have suggested the existence of a nearby dwarf galaxy associated to the Canis Major overdensity, which was tidally disrupted leaving remnants throughout the Monoceros ring observed along several positions within ~20 degrees from the Galactic plane. Here, we present arguments to think that the Canis Major overdensity is just a part of the Galactic warp+flare, instead of a dwarf galaxy or a new substructure in the Galaxy, and the Monoceros ring overdensities and its features on color-magnitude diagrams are mainly populations of the most external non-truncated flared thin+thick stellar disc. Failures to fit these features with the Milky structure stem mainly from the use of Galactic models which do not represent appropriately the southern warp, the disc flare, and that set an unrealistic truncation of the stellar populations of the disc at R=14 kpc, like the Besançon model.
19.11.12 (Monday)
12:00
"Canis Major overdensity and Monoceros ring explained in terms of pure Milky Way structure"
Martin LOPEZ CORREDOIRA (IAC)
Abstract
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"Canis Major overdensity and Monoceros ring explained in terms of pure Milky Way structure"

Martin LOPEZ CORREDOIRA (IAC)

Abstract

Some authors have suggested the existence of a nearby dwarf galaxy associated to the Canis Major overdensity, which was tidally disrupted leaving remnants throughout the Monoceros ring observed along several positions within ~20 degrees from the Galactic plane. Here, we present arguments to think that the Canis Major overdensity is just a part of the Galactic warp+flare, instead of a dwarf galaxy or a new substructure in the Galaxy, and the Monoceros ring overdensities and its features on color-magnitude diagrams are mainly populations of the most external non-truncated flared thin+thick stellar disc. Failures to fit these features with the Milky structure stem mainly from the use of Galactic models which do not represent appropriately the southern warp, the disc flare, and that set an unrealistic truncation of the stellar populations of the disc at R=14 kpc, like the Besançon model.
22.11.12 (Thursday)
12:00
"Beyond the 2-HA Rule: Revisiting the Impact of Atmospheric Effects on VIMOS-MOS Observations"
Ruben SANCHEZ-JANSSEN (ESO, Chile)
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"Beyond the 2-HA Rule: Revisiting the Impact of Atmospheric Effects on VIMOS-MOS Observations"

Ruben SANCHEZ-JANSSEN (ESO, Chile)

Abstract

It is well known that atmospheric effects (differential refraction and atmospheric dispersion) impose severe constraints on multi-object spectroscopic (MOS) observations, where the two joint effects cannot be corrected. Flux losses must then be minimised by a careful optimisation of observing conditions -- and this is especially true for instruments that use slits (instead of fibres), where field rotation prevents the alignment of all slits along the parallactic angle. This is the case of VIMOS at the VLT, where MOS observations have been restricted since the start of operations to within 2 hours from meridian crossing. In the context of the ongoing VIMOS Upgrade Project we have revisited this problem through modelling of slitlosses under different observational conditions. We will show that under relatively common circumstances observations can be extended to larger hour angles, increasing target observability and therefore improving the instrument's efficiency.
23.11.12 (Friday)
10:00
"Quasar Absorption Lines" (Lecture 2)
Sebastian LOPEZ (Universidad de Chile)
Abstract
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"Quasar Absorption Lines" (Lecture 2)

Sebastian LOPEZ (Universidad de Chile)

Abstract

How do galaxies accrete their gas to form stars? What Galaxy/Intergalactic-Medium interplay drives their evolution? The quasar absorption lines technique has proven to be a powerful tool to assess these fundamental questions. In these two lectures at the graduate level I will give a broad overview of the QAL technique and its several applications to the above problems.
26.11.12 (Monday)
12:00
"Disks and other Asymmetries from the AGB and beyond"
Foteini LYKOU (University of Manchester)
Abstract
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"Disks and other Asymmetries from the AGB and beyond"

Foteini LYKOU (University of Manchester)

Abstract

There has been much debate on the shaping mechanisms that modify the circumstellar envelopes of evolved stars into asymmetric structures. Over the last years theoretical and observational studies have shown that binarity is the most probable agent in shaping the ejecta into bipolar, multipolar and/or irregular nebulae. Part of the circumstellar envelope does settle in equatorial structures, such as disk, tori and spirals. In an effort to further understand the shaping mechanism, we have mapped the vicinity of evolved stars from the AGB phase and beyond with the use of infrared interferometry with the VLT and the VLTI. We have detected disk-like structures in our sample of evolved stars and I will present the results of our recent studies.
29.11.12 (Thursday)
12:00
"Monte Carlo simulations and their applications on planetary periodic signals"
Matias JONES (ESO, Chile)
Abstract
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"Monte Carlo simulations and their applications on planetary periodic signals"

Matias JONES (ESO, Chile)

Abstract

In this talk I will briefly describe what Monte Carlo simulations are and present some basic applications. I will then focus the discussion on the use of random numbers to derive detectability limits for periodic radial velocity signals induced by planets.

October 2012

1.10.12 (Monday)
12:00
"Global gas and dust budgets of Magellanic Clouds "
Mikako MATSUURA (University College London, UK)
Abstract
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"Global gas and dust budgets of Magellanic Clouds "

Mikako MATSUURA (University College London, UK

Abstract

Within galaxies, gas and dust are constantly exchanged between stars and the interstellar medium (ISM). The life-cycle of gas and dust is the key to the evolution of galaxies. Despite its importance, it is has been very difficult to trace the life-cycle of gas and dust via observations. The Spitzer Space Telescope and Herschel Space Observatory have provided a great opportunity to study the life-cycle of the gas and dust in very nearby galaxies, the Magellanic Clouds. We have accounted gas and dust ejected from asymptotic giant branch (AGB) stars (Low- and intermediate-mass stars) against supernova (SNe), high mass origin, and compared with the gas and dust mass present in the ISM, as well as the star-formation rate. It appears that Magellanic Clouds underwent have different dust enrichment process from the Milky Way. I briefly talk about prospects with the ALMA observations.
2.10.12 (Tuesday)
12:00
"The Metallicity Planet Correlation In The Harps Volume Limited Sample"
Sergio SOUSA (University of Porto)
Abstract
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"The Metallicity Planet Correlation In The Harps Volume Limited Sample"

Sergio SOUSA (University of Porto)

Abstract

To understand the formation and evolution of solar-type stars and planets in the solar neighborhood, we need to obtain their stellar parameters with high precision. We present a catalog of precise stellar parameters for the FGK stars in a volume limited sample followed by the HARPS spectrograph in the quest for extra solar planets. The spectroscopic analysis was completed assuming LTE with a grid of Kurucz atmosphere models and using the ARES code for an automatic measurement of the line equivalent widths. The results are compared against different independent methods and also with other values that are found in the literature for common stars. Both comparisons are consistent and show the homogeneity of the parameters derived by our team. The derived metallicities in this sample reveal a somewhat different distribution for the present planet hosts, but still indicates the already know higher frequency of planets observed for the more metal rich stars. We combine the results derived in this sample with the one from CORALIE survey to present the largest homogeneous spectroscopic study of the metallicity-giant planet relation.
11.10.12 (Thursday)
12:00
"Weighing the Milky Way using Tidal Tails of Globular Clusters"
Andreas KUEPPER (AIfA, Universität Bonn, Germany)
Abstract
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"Weighing the Milky Way using Tidal Tails of Globular Clusters"

Andreas KUEPPER (AIfA, Universität Bonn, Germany)

Abstract

The distribution of mass within the Milky Way halo is an important but largely unknown quantity. Stellar streams of Galactic satellites, such as the Sagittarius stream, offer a possibility to infer the Galactic mass distribution. Such streams trace their progenitor’s orbits about the Galaxy. From numerical modeling of stellar streams we can gain orbital information of the progenitor satellite and, finally, deduce the underlying Galactic mass distribution. I will demonstrate that the most powerful streams for measuring the Galactic mass distribution are tidal tails originating from globular clusters. These tidal tails are kinematically much colder and thinner than, e.g., the Sagittarius stream. Hence, they yield tighter orbital constraints. In addition, globular cluster tidal tails exhibit dynamical substructures, which contain unique orbital information. Using the example of the outer-halo globular cluster Palomar 5, I will show how this information can be extracted and used to weigh the Milky Way.
23.10.12 (Tuesday)
12:00
"A close look at nearby ‘Seyfert 2’ nuclei"
Semir SMAJIC (University of Cologne)
Abstract
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"A close look at nearby ‘Seyfert 2’ nuclei"

Semir SMAJIC (University of Cologne)

Abstract

The NIR is less influenced by dust extinction than optical light which enables us to look through dusty regions. In addition, it is sensitive to the mass-dominating stellar population. The combination of NIR imaging and spectroscopy gives us the opportunity to analyze several emission and absorption lines and to investigate the stellar population and ionization mechanisms over a field of view (FOV) of 4x4 arcsec. We detect several emission lines ([Si vi], Paα, Brγ, H2, [Fe ii]) and analyze these in terms of excitation to disentangle the ionization mechanisms and velocity. We use the absorption features of Si i, CO(6-3) and CO(2-0) to determine the stellar population. We use the large wavelength range of H+K-band and the stellar absorption features to do a continuum synthesis. We fit a stellar, dust and power-law contribution together with an extinction component. The result presents regions dominated by the different contributors and extinction information over the full field of view.
25.10.12 (Thursday)
12:00
"The central density of R136 in 30 Doradus"
Fernando SELMAN (ESO, Chile)
Abstract
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"The central density of R136 in 30 Doradus"

Fernando SELMAN (ESO, Chile)

Abstract

The central density rho_0 of a stellar cluster is an important physical parameter to determine its evolutionary and dynamical state. The degree of mass segregation, or whether the cluster has undergone core collapse both depends on rho_0. We reanalyze the results of a previous paper that gives the mass density profile of R136 and combine them with both a conservative upper limit for the core parameter and a more uncertain recent measurement. We thus place a lower limit on rho_0 under reasonable and defensible assumptions about the IMF and its extrapolation to lower masses finding rho_0 >~ 1.5x10^4 Msun/pc^3 for the conservative assumption a < 0.4 pc for the cluster core parameter. If we use the smaller, but more uncertain value a = 0.025 pc, the central density estimate becomes larger than 10^7 Msun/pc^3. A mechanism based on the destruction of a large fraction of circumstellar disks is posited to explain the hitherto unexplained increase in reddening presented in that same work.

September 2012

11.09.12 (Tuesday)
12:00
"Studying stellar groups in spiral galaxies"
Gustavo BAUME (Universidad de La Plata, Argentina)
Abstract
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"Studying stellar groups in spiral galaxies"

Gustavo BAUME (Universidad de La Plata, Argentina)

Abstract

Since a large fraction of the star formation take place in spiral galaxies, we are conducting a study on some closest galaxies where we are cataloging and analyzing their stellar groups looking for the young ones. The research is carried out using high quality observations in several bands. They allow then to obtain magnitudes and colors of thousands of almost individual sources. The distance and inclination of selected galaxies were appropiate to search for stellar clusters, to build their radial density profiles and to discriminate among them by their colors. Photometric diagrams of the stellar groups and their surrounding fields allow to estimate the basic parameters of the stellar groups and the features of galactic stellar populations.
12.09.12 (Wednesday)
16:00
"Lyman-alpha diagnostics in the epochs of galaxy formation and cosmic reionization"
Matthew HAYES (OMP)
Abstract
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"Lyman-alpha diagnostics in the epochs of galaxy formation and cosmic reionization"

Matthew HAYES (OMP)

Abstract

By necessity the epochs of rapid galaxy growth/assembly and cosmic reionization were coeval, at roughly redshift z~6-11. While the focus of huge observational onslaughts in the last decade, many pieces of this puzzle remain far from constrained empirically. A non-exhaustive list includes the gas and dust content of young galaxies, the geometry of the circumgalactic medium, the physical mechanisms by which dark matter haloes acquire the gas they need to form galaxies, and the reionization history. In my talk I will present and discuss new observational and modelistic methods by which all of these quantities can be studied, united by the common theme of a single emission line: the n=2-1 transition of neutral hydrogen (HI Lyman-alpha).
26.09.12 (Wednesday)
16:00
"The diffuse intergalactic light in rich clusters of galaxies as a fossil record of their mass-assembly history"
Jorge MELNICK (ESO, Chile)
Abstract
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"The diffuse intergalactic light in rich clusters of galaxies as a fossil record of their mass-assembly history"

Jorge MELNICK (ESO, Chile)

Abstract

Within the LCDM paradigm, structure formation in the Universe is a hierarchical process where structures grow through successive mergers of initially pure dark matter halos. The hierarchy presumably starts with small halos of masses not larger than a few million Msun and ends with the formation of the most massive clusters of galaxies with masses a hundred million times larger. The Coma cluster, for example, has a mass of about 4x10^14 Msun. As times goes by, the largest galaxies near the cluster centers merge to form gigantic cD galaxies, which will continue to grow by cannibalizing most of the cluster members. The comparison between models and observations is not straightforward because, while N-body calculations of the evolution of dark-matter are mostly limited by computing power, modelling the evolution of gas and stars is limited by the still incomplete knowledge of the physics of the Baryonic component (e.g. star-formation; feed-back; etc.). The situation has improved significantly in the past few years owing to more realistic models using higher resolution dark-matter simulations with realistic semi-analytic treatment of the Baryonic physics. In particular, the latest models including the processes of AGN feedback and star-formation quenching predict that more than 50% of the stars in rich clusters of galaxies should be unbound from galaxies and free-floating in the intra-cluster medium. In other words, a significant fraction of the luminousity of clusters of galaxies should be in the form a diffuse inter-galacitic component permeating the clusters. In this talk I will show that although this diffuse intra-cluster light (ICL) component is extremely faint, it is possible with 8m-class telescopes and long exposures to obtain spectra of sufficient quality to allow population synthesis studies of the age and chemical composition of the ICL stars for clusters at `interesting' redshifts (0.15-0.4). In particular, I will exhibit a recent study of one such cluster at z=0.3 and compare the results with the predictions of state-of-the art LCDM structure formation models.

August 2012

13.08.12 (Monday)
12:00
"The extinction curve towards the Galactic Center"
Tobias FRITZ (MPE)
Abstract
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"The extinction curve towards the Galactic Center"

Tobias FRITZ (MPE)

Abstract

First I introduce the Galactic Center in general. For much of the science about the Galactic Center it is important to know the wavelength dependent extinction towards the Galactic Center. Therefore, I derive the extinction curve towards the Galactic Center from 1 to 19 micron. For the extinction measurement I use fluxes of the HII region (the minispiral) in the Galactic Center. The intrinsic flux ratios of the different tracers of the minispiral are well known and the deviations are caused by extinction. I use hydrogen emission lines of the minispiral observed by ISO-SWS and SINFONI. As extinction free flux reference I use the 2 cm continuum emission observed by the VLA. I use the extinction measurement for obtaining a photometric distance to GC. Further I constrain the dust composition towards the GC by using the wavelength dependence of the extinction.
14.08.12 (Tuesday)
12:00
"Dynamical secrets of the Arches cluster"
Christoph OLCZAK (Heidelberg University)
Abstract
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"Dynamical secrets of the Arches cluster"

Christoph OLCZAK (Heidelberg University)

Abstract

Clustered modes of star formation are dynamically active environments which is most evident for the extremely dense starburst clusters. Combining observational data and detailed numerical models of the Arches cluster I will present two exciting effects of stellar dynamics operating on different scales in this prototype Galactic starburst cluster. Microscopically stellar encounters drive the destruction of about one third of the circumstellar discs around young stars in the cluster core within the first 2.5 Myr of evolution, preferentially affecting the least and most massive stars. In addition to the extended tidal tails formed by evaporating stars a small fraction of strong interactions eject disc-poor stars that form a weaker second pair of tidal tails. Macroscopically we find that a significant amount of the dynamical mass of the Arches cluster can be hidden in the yet to be observed rotation of the cluster. This mechanism provides an excellent alternative to explain the seemingly too large photometric mass under the assumption of a standard mass function.
16.08.12 (Thursday)
12:00
"ExELS: A Proposed Euclid Legacy Survey of Cold Exoplanets"
Matthew PENNY (Ohio State University)
Abstract
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"ExELS: A Proposed Euclid Legacy Survey of Cold Exoplanets"

Matthew PENNY (Ohio State University)

Abstract

Euclid is an ESA M-class mission to study dark energy by performing a wide-field, optical-near-IR survey for weak lensing and baryon acoustic oscillations. A portion of Euclid's time will be used for additional Legacy Science. Its wide-field, near-IR capabilities also make Euclid well suited to perform an exoplanet microlensing survey. ExELS is a Euclid Legacy Science proposal to survey the cold exoplanet population down to Earth masses and below. In this talk I will describe the proposed survey and the expected scientific returns.
20.08.12 (Monday)
12:00
"ESPRESSO – a science machine for the ESO VLT"
Guido CUPANI (Observatory of Trieste, Italy)
Abstract
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"ESPRESSO – a science machine for the ESO VLT"

Guido CUPANI (Observatory of Trieste, Italy)

Abstract

The Echelle SPectrograph for Rocky Exoplanets and Stable Spectral Observations (ESPRESSO) is a groundbreaking instrument currently in the design phase for the ESO VLT Combined Coudé Laboratory. It integrates an extreme thermal and mechanical stability with the capability of acquiring high-resolution spectra in the range from 380 to 780 nm, receiving the light from up to four UTs at once. The scientific drivers beyond this design are 1. to measure high precision radial velocity as a way to find rocky exoplanets; 2. to measure the possible variation of fundamental constants; and 3. to analyze the chemical composition of stars in nearby galaxies. In this sense, ESPRESSO is going to pave the way to the upcoming spectrographs of the ELT era (like CODEX). In this talk, I will present the details of the ESPRESSO project with a particular focus on the data analysis software, the first of its kind for an ESO instrument. A preview of the operating continuum-fitting algorithm for quasar spectra will be shown during the talk.
22.08.12 (Wednesday)
16:00
"Laser frequency combs as calibrators for Astronomy"
Gaspare LO CURTO (ESO, Garching)
Abstract
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"Laser frequency combs as calibrators for Astronomy"

Gaspare LO CURTO (ESO, Garching)

Abstract

Laser frequency combs are the new technology for top precision metrology. They can be also coupled to a spectrograph and serve as calibrators for high precision spectroscopy, from atomic and molecular spectroscopy in the laboratory to spectroscopy of celestial objects. The precision achievable in astronomical spectroscopy assisted by laser frequency combs gives the possibility to address various scientific questions from the field of exoplanets to stellar physics to cosmology. I will describe how a laser comb for astronomy works, the advantages with respect to more traditional calibration methods, and the way such a device can be coupled to an astronomical spectrograph. In particular I will describe what we are learning from our tests of the laser frequency comb on HARPS.
23.08.12 (Thursday)
12:00
"News on Supernova 1987A"
Jacco VAN LOON (Keele University, UK)
Abstract
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"News on Supernova 1987A"

Jacco VAN LOON (Keele University, UK)

Abstract

In 1987 a supernova was seen in the Large Magellanic Cloud, presenting the unique opportunity to follow in exquisite detail the early development of a supernova remnant. I will present results from new radio, (sub)mm and infrared observations of the changing environment of Supernova 1987A, with emphasis on the dust and shocks in the system and the mass loss from the supernova progenitor. I will also place SNR1987A in the context of the Magellanic supernova remnant populations and the evolution of galaxies.
24.08.12 (Friday)
12:00
"Massive Young Stellar Objects in the Magellanic Clouds"
Joana OLIVEIRA (Keele University, UK)
Abstract
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"Massive Young Stellar Objects in the Magellanic Clouds"

Joana OLIVEIRA (Keele University, UK)

Abstract

I present recent work on the identification and characterisation of massive Young Stellar Objects in the Small Magellanic Cloud. Starting from a photometric selection, Spitzer-IRS and VLT/ISAAC spectra are used to constrain the YSOs' evolutionary status. I will describe the analysis of PAH and molecular hydrogen emission properties. Further I will focus on the analysis of water, CO and CO2 ice features and the comparison of such features in SMC, LMC and Galactic environments.
27.08.12 (Monday)
12:00
"The dynamic atmospheres of Mira stars"
Michel HILLEN (Katholieke Universiteit Leuven)
Abstract
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"The dynamic atmospheres of Mira stars"

Michel HILLEN (Katholieke Universiteit Leuven)

Abstract

In spite of their great astrophysical importance, many aspects of AGB stars, and Miras in particular, remain poorly understood. The luminous Miras represent a non-negligible fraction of the luminosity budget of many (un)resolved stellar populations. Moreover, due to their high mass-loss rates they contribute actively in replenishing the interstellar medium with "processed material" resulting from the rich internal nucleo-synthesis and strong dust processing in the cool outer environment. Many questions remain about the details of all these aspects. In particular, our understanding of the structure of the atmosphere, which provides the link between the enriched stellar interior and the evolution-dominating wind, is at a turning point thanks to the maturing of many 'new' observational techniques and the availability of a new generation of atmosphere models. In this talk, I will present our recent effort to confront the latter, i.e. to compare CODEX models to interferometric time series.
28.08.12 (Tuesday)
12:00
"Revealing the Diversity of Super-Earth Atmospheres"
Jacob BEAN (University of Chicago)
Abstract
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"Revealing the Diversity of Super-Earth Atmospheres"

Jacob BEAN (University of Chicago)

Abstract

Recent surveys have revealed an amazing, and yet unexplained, diversity of low-mass planets orbiting other stars. Atmospheric studies hold the promise of revealing the nature and origins of these mysterious worlds, and such investigations are possible for a few select objects with current ground- and space-based telescopes using the technique of transit spectroscopy. I will present the results from the first observations of the atmosphere of a super-Earth type planet, the intriguing GJ1214b. The data obtained to date have revealed that this planet either has an atmosphere of super-heated water vapor, or is cloaked in clouds or hazes of unknown composition. I will describe the additional observations that are needed to definitively reveal the composition of GJ1214b's atmosphere. I will also discuss how the comparative exoplanetology enabled by similar proposed studies of other super-Earths can significantly advance our knowledge of a class of planets that is not represented in the Solar System. I will conclude with a look ahead at what steps are necessary to be ready to characterize potentially habitable exoplanets using the same observational approach with JWST.
30.08.12 (Thursday)
12:00
"Measuring magnetic fields in the central stars of planetary nebulae"
Marian MARTÍNEZ (Instituto de Astrofísica de Canarias)
Abstract
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"Measuring magnetic fields in the central stars of planetary nebulae"

Marian MARTÍNEZ (Instituto de Astrofísica de Canarias)

Abstract

A large fraction of planetary nebulae (about 80%) are bipolar or elliptical rather than spherically symmetric. Modern theories invoke magnetic fields, among other causes, to explain the rich variety of aspherical components observed in PNe, as ejected matter is trapped along magnetic field lines. But, until recently, this idea was mostly a theoretical claim. Jordan et al. (2005) report the detection of kG magnetic fields in the central star of two non-spherical PNe, namely NGC1360 and LSS1362. We find that, contrary to that work, the magnetic field is null within errors for both stars. Then, the role of magnetic fields in shaping planetary nebulae is still an open question. In this talk I will show our robust method to infer magnetic fields in the central stars of planetary nebula. Although applied to this field, this inference technique, based on a bayesian scheme, is general and can be applied to any astrophysical object.

July 2012

3.07.12 (Tuesday)
12:00
"Connecting Star Formation and AGN in Active Galaxies"
Eleonora SANI (Arcetri Observatory)
Abstract
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"Connecting Star Formation and AGN in Active Galaxies"

Eleonora SANI (Arcetri Observatory)

Abstract

Two main physical processes characterize the activity in the nuclear region of Active galaxies: an intense star formation (starburst, SB), and an Active Galactic Nucleus (AGN). There is increasing evidence of a strong link between the SB and AGN mechanism in active galaxies. Moreover the issue of SB-AGN connection in local and distant galaxies is relevant for understanding galaxy formation and evolution, the star formation and metal enrichment of the Universe, and the origin of extragalactic background. Thus, it is crucial to develop precise and effective observational methods in order to estimate the AGN/SB content in active galaxies. Here I explore this issue reviewing the most recent techniques, and discuss the resuls obtained for samples of active galaxies in the local and high-redshift Universe.
4.07.12 (Wednesday)
16:00
"UVES reveals the extended chromosphere of CoRoT-2A"
Stefan CZESLA (Hamburg Observatory)
Abstract
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"UVES reveals the extended chromosphere of CoRoT-2A"

Stefan CZESLA (Hamburg Observatory)

Abstract

I present the detection of an extended chromosphere in the active planet host-star CoRoT-2A. The CoRoT-2 system consists of a young, highly active G7V star and an unusually inflated hot Jupiter. The 140 d long CoRoT light curve shows substantial stellar variability and deep planetary transits deformed by starspot occultations, which we analyzed to reconstruct the surface spot-evolution. Chandra X-ray observations obtained by our group show strong coronal X-ray emission from the host star, CoRoT-2A, and an unexpectedly inactive optical and likely physical stellar companion. Using transit spectroscopy obtained with UVES, we probe CoRoT-2A's chromosphere through the analysis of the radial velocity shift measured in the Ca~II emission-line cores. We find a chromospheric Rossiter-McLaughlin effect showing a prolonged transit in the Ca~II emission-line cores. Our results indicate that CoRoT-2A's chromosphere extends about 0.16 stellar radii beyond the photospheric radius.
6.07.12 (Friday)
13:00
"L'Harmonie des Sphères : From Pythagoras to Voyager 2"
Dominique PROUST (Paris-Meudon Observatory)
Abstract
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"L'Harmonie des Sphères : From Pythagoras to Voyager 2"

Dominique PROUST (Paris-Meudon Observatory)

Abstract

From Pythagoras who tried to find a general theory of the World, until now, many musicians have raised the ideas of the Harmony of the World taking inspiration from the celestial mechanics. Conversely, many astronomers were interested by the musical harmonics relations e.g. the musical scale, to explain the movements of the planets. Through the History, old greeks such as Pythagoras, Platon, Ptolemee, medieval astronomers and neoplatonicians, then Copernic, Kepler, Galilee, explained the universe with a musical, harmonic concept. More recently, the first cosmologists such as William Herschel, until the contemporary period have associated musical (harmonic) principles (e.g. the Bode's law). Today, the two spacecrafts Voyager transport a videodisk containing Earth musical samples as a universal language with hypothetic extraterrestrial civilizations.
17.07.12 (Tuesday)
12:00
"The polarimeters for HARPS and X-shooter"
Frank SNIK (Sterrewacht Leiden)
Abstract
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"The polarimeters for HARPS and X-shooter"

Frank SNIK (Sterrewacht Leiden)

Abstract

Spectropolarimetry enables observations of stellar magnetic fields and circumstellar asymmetries, e.g. in disks and supernova explosions. To furnish better diagnostics of such stellar physics, we designed and commissioned a polarimetric unit at the successful HARPS spectrograph at ESO's 3.6-m telescope at La Silla. I will present the design and performance of HARPSpol, and show some first science results. The most striking achievement of HARPSpol is its capability to measure stellar magnetic fields as small as 0.1 G. I will also give a sneak preview of the polarimeter we are currently designing for X-shooter at the VLT. It contains a novel type of polarimetric modulator that is able to efficiently measure all the Stokes parameters over the huge wavelength range of 300--2500 nm.
19.07.12 (Thursday)
12:00
"Quasars in the Epoch of Reionisation"
Bram VENEMANS (Max Planck Institute for Astronomy, Heidelberg)
Abstract
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"Quasars in the Epoch of Reionisation"

Bram VENEMANS (Max Planck Institute for Astronomy, Heidelberg)

Abstract

Quasars are the brightest (non-transient) objects observed at the highest redshifts (z>>6). Such high redshift quasars are important as detailed analysis of quasar spectra provide unique information about the baryonic and physical condition of the Universe during the epoch of reionisation. In the last decade around 50 z~6 quasars have been discovered, mostly in large optical surveys such as the Sloan Digital Sky Survey (SDSS). The limitation of optical surveys is that they cannot find quasars beyond z~6.4 as the sources become very faint in the optical bands due to absorption by the intervening Lyman-alpha forest. In this talk I will present the successes of recent near-infrared surveys aimed at discovering bright quasars at redshifts z>6.5, and the implications of the results on models of galaxy and quasar evolution.
20.07.12 (Friday)
12:00
"The nearby population of M-dwarfs with WISE: A search for mid-infrared excesses"
Henning AVENHAUS (ETHZ, Switzerland)
Abstract
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"The nearby population of M-dwarfs with WISE: A search for mid-infrared excesses"

Henning AVENHAUS (ETHZ, Switzerland)

Abstract

Circumstellar debris disks have been studied for their connection and interaction with planetary systems. An efficient way to identify such systems is through their infrared excess. Most studies so far concentrated on early-type or solar-type stars, but little eff ort has gone into M dwarfs, which have the additional problem that the mid-infrared colors are poorly known. I will describe an effort to identify such excess stars amongst the nearby M dwarfs using data from the WISE sattelite and a data-driven calibration of the M-dwarf mid-infrared colors as well as the statistical implications of the results and implications for future excess studies.
25.07.12 (Wednesday)
16:00
"Magnetic fields in T Tauri stars"
Gaitee HUSSAIN (ESO, Garching)
PRESENTATION
Abstract Stellar magnetic fields play a key role in the early stages of star formation. Magnetic fields are believed to control accretion from circumstellar disks. This magnetospheric accretion regulates the angular momentum evolution in low mass stars, though the exact mechanism by which this is done is as yet unclear. I will give an overview of the latest results from our programme, MaPP, which has enabled us to map magnetic fields in a range of T Tauri star systems. I will particularly focus on magnetic fields and accretion in young intermediate mass stars. They will become A-type stars on the main sequence but possess many properties similar to those of lower mass systems in the pre-main sequence stages.

6.06.12 (Wednesday)
16:00
"The mid-IR emitting source in AGN -- it's getting windy"
Sebastian HOENIG (University of California, Santa Barbara)
Abstract
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"The mid-IR emitting source in AGN -- it's getting windy"

Sebastian HOENIG (University of California, Santa Barbara)

Abstract

Significant progress in our understanding of the dusty environment around AGN has been made over the last years, thanks to high-spatial resolution capabilities in the infrared at the VLT and VLTI. The source of emission in the infrared is commonly believed to be the "dust torus", one of the cornerstones of AGN unification, located in the equatorial plane around the accretion disk and broad-line region. However, recent observations with the VLTI indicate that the torus emission may become energetically minor in a significant part of the infrared. In the talk I will present new results that have the potential to shake up some long-standing paradigms about the origin of the mid-IR emission in AGN. 

June 2012

7.06.12 (Thursday)
12:00
"The extinction map of the Arches starburst cluster in the Galactic center"
Maryam HABIBI (Bonn University)
Abstract
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"The extinction map of the Arches starburst cluster in the Galactic center"

Maryam HABIBI (Bonn University)

Abstract

The Galactic center is the most active site of star formation in the Milky Way Galaxy, where particularly high-mass stars have formed very recently and are still forming today. However, since we are looking at the Galactic center through the galactic disk , knowledge of extinction is crucial to study the region. The Arches cluster is a young, massive starburst cluster, near the Galactic center. We look at the Arches cluster in a wider area around the core using Ks band imaging data obtained with NAOS/CONICA at the VLT combined with Subaro/Cisco J band data to obtain the extinction map of the Arches cluster. We established the importance of extinction knowledge by deriving the individual extinction values and masses by assuming two commonly used extinction laws presented by Rieke & Lebofskey (1985) and Nishiyama et al.(2009). We show that the difference can reach up to 30% in extracted initial mass and 0.93 magnitude in acquired k band extinction ,corresponding to a visual extinction difference of up to 10 mag, while the initial mass function slope does not change dramatically.
12.06.12 (Tuesday)
12:00
"A stroll through the dust shells of AGB stars"
Daniela KLOTZ (University of Vienna)
Abstract
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"A stroll through the dust shells of AGB stars"

Daniela KLOTZ (University of Vienna)

Abstract

Asymptotic Giant Branch (AGB) stars are subject to heavy stellar mass loss that is responsible for the formation of circumstellar shells. Even though mass loss has been studied for over four decades, many aspects are still poorly understood. One of these aspects is the spherical/aspherical geometry of the envelope around AGB stars. An international team of astronomers is currently involved in a VLT(I) large program with the goal to study the geometry of the dust shells around AGB stars. This goal will be achieved by combining observations of 15 stars taken with VLTI/MIDI, VLT/VISIR and the Herschel satellite. In this talk I am going to introduce the basic idea of this large program and recent interferometric results related to this study will be presented. 
26.06.12 (Tuesday)
12:00
"Probing dusty circumstellar environments with polarimetric aperture-masking interferometry"
B. NORRIS (Sydney Observatory)
Abstract
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"Probing dusty circumstellar environments with polarimetric aperture-masking interferometry"

B. NORRIS (Sydney Observatory)

Abstract

Aperture-masking interferometry allows diffraction-limited images to be recovered despite the turbulent atmosphere. We have combined this with polarimetry to form a novel technique allowing the dusty environments of mass-losing stars (so-called AGB stars) and proto-planetary and debris disks to be imaged, the characterisation of which is key to understanding the recycling of matter and the formation of new planetary systems. Polarimetric aperture-masking interferometry produces images by exploiting the fact that starlight scattered by circumstellar dust becomes strongly polarised. Essentially, aperture-masking allows access to the small spatial scales (~10mas) necessary while polarimetry allows light from the dust and star to be differentiated. Furthermore, measurements at multiple wavelengths allow dust grain sizes to be calculated using Mie scattering theory. Excellent results have already been obtained at near-IR wavelengths using the NACO instrument at the VLT. The next step is to leverage the higher spatial resolution and polarisation signal found in the visible, rather than near-IR. To this end, a new instrument allowing precision polarimetric aperture masking interferometry at 600-800nm is being developed for an 8m class telescope, details of which will also be presented.
28.06.12 (Thursday)
12:00
"The mid-infrared properties of local active galactic nuclei"
Daniel ASMUS (Kiel University, Germany)
Abstract
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"The mid-infrared properties of local active galactic nuclei"

Daniel ASMUS (Kiel University, Germany)

Abstract

The local active galactic nuclei (AGN) population enables us to study in detail the structures and radiation processes in the direct environment of the supermassive black holes in galaxy centers and to develop an understanding of the general AGN phenomenon. For this purpose, the first unbiased sample of 104 local AGN has now become available thanks to Swift/BAT observations in the hard X-ray regime. We performed high-angular resolution mid-infrared (MIR) imaging observations of most of these AGN with VLT/VISIR and Gemini/Michelle in order to study the dusty tori in these objects – a key component in AGN models. At the same time, we obtained similar data of a complementary sample of AGN in the low-luminosity regime. I present the results of both programmes and show that unresolved MIR emission is present in the AGN of both samples, which is consistent with thermal emission from dust in the direct vicinity of the AGN. Furthermore, the MIR emission is strongly correlated with the absorption-corrected 2-10 keV X-ray emission over the whole range of luminosities (10^40 to 10^45 erg/s). These results agree with the standard unification model being valid for all types of AGN without major modifications.

Mai 2012

02.05.12 (Tuesday)
17:00
"Modes of mass-loss from microquasars"
Katherine BLUNDELL (Oxford University)
Abstract
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"Modes of mass-loss from microquasar"

Katherine BLUNDELL (Oxford University)

Abstract

Black holes in our Galaxy, such as those in the microquasars SS433 and Cygnus X-3, demonstrate dynamic behaviour in accretion and dramatic mass outflows. We observe winds and relativistic plasma jets to emerge from these objects which resemble the modes of mass-loss in the supermassive black holes of powerful quasars in the distant universe. Time-resolved observations of the accretion and subsequent mass-loss from microquasars offers great rewards in terms of information about the nature of these remarkable phenomena in the Universe. I will describe how combined multi-wavelength strategies across the electromagnetic spectrum continue to yield new discoveries and discuss how time-resolved observations have led to the discovery of a further mode of mass-loss in SS433 via a circumbinary disc. I shall present the exquisitely detailed behaviour of these modes of mass-loss before, during and after a major flare event in this object, gleaned from data from other wavebands as well as via spectroscopy from La Serena and NACO imaging from Paranal.
09.05.12 (Wednesday)
16:00
"The Lithium content of globular clusters and in giant stars"
Lorenzo MONACO (ESO)
Abstract
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"The Lithium content of globular clusters and in giant stars"

Lorenzo MONACO (ESO)

Abstract

Globular clusters (GCs) are among the oldest objects in the universe. By studying their Li content, insights can be gained about both the cosmological Lithium problem ---namely the discrepancy between the Li abundance predicted by standard big bang nucleosynthesis coupled with the baryonic density measured by WMAP and the constant value observed in warm metal poor halo stars, i.e. the Spite plateau--- and about the ubiquitous multi-population identified in GCs and, hence, about their chemical enrichment history. I will present the results of two spectroscopic campaigns aimed at studying the Li content of unevolved stars in the GCs WCen and M4. Additionally, I will also present the results of a search for Li-rich giants among thick disk stars. An overall dilution of the stellar lithium content happens as soon as a star evolve off the main sequence. Nevertheless, a few percent of giant stars present high lithium abundances, which origin is not yet completely understood, at least for low mass stars.
11.05.12 (Friday)
16:00
"Curious, these inflated hot Jupiters..."
Henk SPRUIT (MPI)
Abstract
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"Curious, these inflated hot Jupiters..."

Henk SPRUIT (MPI)

Abstract

We propose that hot Jupiters with inflated sizes represent a separate planet formation channel: the merging of two low-mass stars. The abundance and properties of W UMa stars and low mass detached binaries are consistent with their being possible progenitors. Several Jupiter-mass planets can form in the massive compact disk formed in a merger event. Gravitational scattering between them can explain the high incidence of excentric, inclined, and retrograde orbits. If the population of inflated planets is indeed formed by a merger process, their frequency should be much higher around blue stragglers than around T Tauri stars. 
15.05.12 (Tuesday)
12:00
"Weak-G band stars : understanding the puzzle"
Ana PALACIOS (University of Montpellier)
Abstract
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"Weak-G band stars : understanding the puzzle"

Ana PALACIOS (University of Montpellier)

Abstract

The weak G-band subclass includes about thirty cool and luminous stars that exhibit very weak or no G-band of the CH. In addition to their apparently very strong carbon deficiency a large number of these stars are also lithium-rich (A(Li) > 1.4 dex). In this presentation, we will review the evolutionary status and the possible explanation of the weak G-band phenomenon, and propose some clues to their lithium enrichment in the light of new stellar evolution models and abundance determinations. 
17.05.12 (Thursday)
12:00
"Globular clusters in our backyard elliptical"
Ricardo SALINAS (University of Turku)
Abstract
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"Globular clusters in our backyard elliptical"

Ricardo SALINAS (University of Turku)

Abstract

At a distance of only ~2.7 Mpc, Maffei 1 is our closest elliptical galaxy. This advantage has been overshadowed by its difficult relative position in the sky; at a Galactic latitude of only b=0.5, the extinction in optical bands can be as high as five magnitudes. The high extinction, together with high contamination from the Galactic plane has made the measurement of even its most basic parameters a difficult and uncertain task. For example, studies of its globular cluster system (GCS) have produced only a handful of globular cluster candidates, whereas for its luminosity, the size of its GCS should be comparable to the one of Cen A, hosting ~1300 GCs. We present the first results of wide-field study of the Maffei 1 GCS conducted using Subaru/SuprimeCam. Based on the slightly non-stellar profiles of the GCs at this distance, we detect a sizeable population across the entire SuprimeCam field of view. 
22.05.12 (Tuesday)
12:00
"Tidal streams and dwarf galaxies in the vicinities of nearby groups"
Johannes LUDWIG (University of Heidelberg)
Abstract
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"Tidal streams and dwarf galaxies in the vicinities of nearby groups"

Johannes LUDWIG (University of Heidelberg)

Abstract

The nearby universe is populated mostly by galaxy groups, whose dominant galaxies are surrounded by numerous dwarf galaxies. We have observed nearby galaxy groups in a distance range of 13 to 34 Mpc with a variety of different morphologies, densities, and richness in order to investigate their dwarf galaxy populations and the resulting environmental effects on the host galaxies. We report about our first results on deep wide-field imaging data of a sample of twelve galaxy groups with a spiral or a S0 as dominant galaxy. One important selection criterion was density. Thus the sample ranges from nearly isolated galaxies to very dense environments. For all of them we were able to detect a considerable number of dwarf companions. Furthermore the host galaxies often show signs of tidal interactions with their dwarf companions. 
29.05.12 (Tuesday)
12:00
"Massive stars in the Milky Way and new selection criteria"
Maria MESSINEO (MPI, Bonn)
Abstract
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"Massive stars in the Milky Way and new selection criteria"

Maria MESSINEO (MPI, Bonn)

Abstract

Massive stars are mostly found in massive clusters, and in proximity of giant HII regions. Thereby, their location is a successful way to select some interesting massive cluster, a natural laboratory for studying stellar evolution. The numbers and spatial distributions of massive stars are quite uncertain, mainly due to our poor knowledge on distances and dust extinction. I will present small review on current census of massive stars/and clusters in the Milky Way and discuss a set of new criteria for finding them. Available new photometric data from large surveys of the Galactic plane (e.g. 2MASS, UKIDSS, VISTA, MSX, and GLIMPSE) allow improving searches for massive stellar clusters and massive stars. These stellar color criteria are very suitable for constructing a 3D view of the inner young stellar population of the Milky Way. On a very large scale, such stars represent a useful calibraton for resolved stars that ELT will observe in far distant galaxies.  
30.05.12 (Wednesday)
16:00
"Long Gamma-Ray Bursts and their associated Supernovae "
Elena PIAN (Scuola Normale Superiore di Pisa, Italy)
Abstract
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"Long Gamma-Ray Bursts and their associated Supernovae "

Elena PIAN (Scuola Normale Superiore di Pisa, Italy)

Abstract

The majority of long duration Gamma-Ray Bursts are associated with energetic Type Ic Supernovae. These are best studied at redshifts lower than 0.3, so that their investigation is based on few rare and precious occurrences, each of which has its own peculiarities. The uniqueness and relative faintness of this class of objects and of their host galaxies makes them primary targets for observations from large telescopes. I will review the results obtained with the VLT.  

April 2012

04.04.12 (Wednesday)
16:00
"Cm-wave continuum radiation from interstellar molecular clouds"
Simon CASASSUS (Universidad de Chile)
Abstract
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"Cm-wave continuum radiation from interstellar molecular clouds"

Simon CASASSUS (Universidad de Chile)

Abstract

An `anomalous' radio continuum was found 15 years ago in the direction of molecular clouds. This emission is consistent with electric dipole radiation from polarized very small grains spinning at GHz frequencies, or `spinning dust'. I will summarise recent observations of this phenomenon, and investigate the nature of the grain spin-up mechanism. The data so far are consistent with grain spin-up from the recoil of H2 formation, or encounters with C+ ions, but not with radiative torques.
10.04.12 (Tuesday)
14:00
"Holographic imaging of dense fields: the amazing poor man's MCAO"
Rainer SHODEL (Instituto de Astrofisica de Andalucia, Granada)
Abstract
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"Holographic imaging of dense fields: the amazing poor man's MCAO"

Rainer SHODEL (Instituto de Astrofisica de Andalucia, Granada)

Abstract

I present an algorithm for speckle holography that has been optimised for crowded fields. The algorithm was tested with different instruments on a range of targets and from the N- to the I-band. In terms of PSF cosmetics and stability as well as Strehl ratio, holographic imaging is equal to, if not superior, to the capabilities of currently available AO systems. It outperforms classical lucky imaging. Holography can relatively easily deal with anisoplanatic effects in dense fields. I will present the exciting results of our tests and will discuss the virtues and vices of the technique. In particular I will address the question in which situations holography can provide unique advantages, or present an alternative or complementary method to the more established techniques such as standard AO imaging or sparse aperture masking. Holography can be used with existing instruments at ESO, such as NACO, VISIR, and HAWK-I.
11.04.11 (Wednesday)
16:00
"The Bowen Survey; detecting donor star signatures in low mass X-ray binaries"
Remon CORNELISSE (IAC, Spain)
Abstract
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"The Bowen Survey; detecting donor star signatures in low mass X-ray binaries"

Remon CORNELISSE (IAC, Spain)

Abstract

I will present results from our optical spectroscopic campaign on Low Mass X-ray Binaries (LMXBs), i.e. compact binaries where the primary is a compact object (a neutron star or black hole) and the secondary a low mass star (<1Msun). Mass is transferred from the secondary onto the compact object forming an accretion disk that gives rise to the observed X-ray. These system represent the endpoint of stellar evolution of massive stars and are key objects to test fundamental physics (in particular General Relativity and the behavior of matter at extreme densities). For most LMXBs the optical emission is dominated by reprocessing of the X-rays in the outer accretion disk. This has severely hampered any dynamical studies and thereby our knowledge of their system parameters. A new avenue opened thanks to the discovery of narrow high-excitation emission components arising from the irradiated companion star. These lines are most prominent in the Bowen region (a blend of NIII and CIII lines between 4630 and 4650 Angstrom). In this talk I will give an extensive introduction into LMXBs, discuss this new technique, give an overview of the main results of our survey on the optically brightest LMXBs, and discuss the implications for their system parameters. Furthermore, I will point out the main limitations of this technique and how they might be overcome.
12.04.12 (Thursday)
12:00
"The low-mass end of the IMF unveiled by the WIRCam/CFHT survey"
Catarina ALVES DE OLIVEIRA (Herschel Science Centre, ESA)
Abstract
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"The low-mass end of the IMF unveiled by the WIRCam/CFHT survey"

Catarina ALVES DE OLIVEIRA (Herschel Science Centre, ESA)

Abstract

Determining the dominant process by which brown dwarfs form is one of the central questions in integrating the substellar regime into our current theoretical framework of star formation. Concurrent brown dwarf formation models must reproduce and predict observable properties of clusters such as the shape of the IMF, multiplicity, mass segregation, frequency and sizes of discs, and accretion. The new observational frontier is therefore the detection and characterization of young very low-mass objects, which can be confronted with model predictions. I will present the results of a major observational study aimed at uncovering the low-mass population of nearby star forming regions. Candidate brown dwarfs have been identified using the WIRCam/CFHT deep near-IR imaging survey complemented with archival data. A spectroscopic follow-up has been conducted using several facilities (TNG, GTC, NTT, VLT, Gemini) to ascertain the spectral types and masses of the candidates. In the first clusters studied, IC 348 and Rho Ophiuchus, we discover new members down to the L dwarf spectral type regime, the least massive known objects in both regions. We do not find evidence for a significant variation or truncation of the low-mass end of the IMF down a few Jupiter masses, concluding that the mass function is similar to other nearby young clusters.
16.04.12 (Monday)
12:00
"Fourier disentangling of SMC eclipsing binaries"
Robert KLEMENT (ESO visiting student)
Abstract
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"Fourier disentangling of SMC eclipsing binaries"

Robert KLEMENT (ESO visiting student)

Abstract

VLT FLAMES archival spectra of several spectroscopic double-line, eclipsing binaries together with photometric observations from the OGLE survey were analyzed using the new code by P. Hadrava (merging his codes KOREL for spectra disentangling and FOTEL for the light-curve solution). Next to the spectra of binary components, the method allows to disentangle circumstellar and/or interstellar lines. By determining distances of the binaries it is possible to put an upper limit on the distance of origin of interstellar absorption. This way, we can complement the radio observations (which show neutral gas distribution in alfa, delta and RV only) and - for the first time- obtain the 3D structure of the SMC interstellar gas.
18.04.12 (Wednesday)
16:00
"Sgr A*: how not to feed a black hole"
Ue-Li PEN (U. Toronto)
Abstract
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"Sgr A*: how not to feed a black hole"

Ue-Li PEN (U. Toronto)

Abstract

We examine the range of astrophysical data on Sgr A*, and highlight the apparent dilemma to explain its low luminosity, 5 orders of magnitude below the predicted Bondi rate. A wide range of theoretical models has been proposed. We study the global problem numerically, and propose a state of magnetically frustrated accretion as the solution. The time variability of rotation measure should distinguish between models. This will be easily resolved by ALMA.
24.04.12 (Tuesday)
12:00
"Recent results of the CoRoT mission"
Juan CABRERA (DLR)
Abstract
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"Recent results of the CoRoT mission"

Juan CABRERA (DLR)

Abstract

CoRoT is a french satellite devoted to the search for planets and the study of asteroseismology of bright stars. I will present some recent results from the science program (like the reobservations of CoRoT-7b and CoRoT-9b) and I will describe the scientific program for the extension of the mission after 2013.
25.04.12 (ednesday)
16:00
"A lack of dark matter in the solar neighborhood"
Christian MONI BIDIN (Universidad de Concepcion)
Abstract
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"A lack of dark matter in the solar neighborhood"

Christian MONI BIDIN (Universidad de Concepcion)

Abstract

Measuring the matter density of the Galactic disk in the proximity of the Sun through stellar kinematics is an old art, now dating nearly a century. We recently re-adress this classical issue estimating the dynamical mass at the solar position up to 4 kpc from the plane. Our calculation relies on a full 3D equation which is exact within the validity of few hypothesis. We find that the solutions strikingly matches the expectation for the visible mass only, and no dark component is required to explain the results. The currenty most popular models of the Galactic dark matter halo are excluded at a level higher than 5 sigmas. I will show the calculations and the results, discussing the hypothesis, the consequences of their break-down, and possible alternatives.

March 2012

01.03.12 (Thursday)
12:00
"Warm CO gas in the planet-forming regions of flaring proto-planetary disks"
Rosina HEIN BERTELSEN (Groningen, The Netherlands)
Abstract CRIRES observations of a small sample of Herbig Ae/Be stars ( Plas et al. 2009, 2011) readily show detections of infrared emission from CO (ro-vibrational transitions) in the inner 50 AU of flat disks, thus making this a powerful tool to understand the physical structure of planet forming regions. Contrary to model expectations and observations of other gas tracers, the CO emission in three flaring Herbig disks is seen to originate further out than seen for flat disks. However, the small number of observed flaring disks hampers our ability to understand this apparent difference and use CO as a general tracer of the inner disk. We propose CRIRES observations of an additional 12 flaring disks as a rigorous test for our hypothesis that ro-vibrational CO emission is only present in the outer parts of flaring disks around Herbig Ae/Be stars. If confirmed, this new correlation could provide first direct evidence for an evolutionary difference between flared and flat disks.
02.03.12 (Friday)
12:00
"Optical imaging with submilliarcsecond resolution: Intensity interferometry with Cherenkov telescopes"
Dainis DRAVINS (Lund University)
PRESENTATION
Abstract Although we do observe starlight, we are still unable - with few exceptions - to observe the stars themselves, i.e., to resolve their disks or view structures across and outside their surfaces. Bright stars have typical sizes of some milliarcsecond(s), and kilometer-scale optical baselines are required for their imaging. However, such phase/amplitude interferometry is hindered by atmospheric turbulence while space interferometry is too complex. Atmospheric effects can be circumvented by intensity interferometry, a technique (once pioneered by Hanbury Brown and Twiss) for measuring the second-order coherence of light. The required large flux collectors are now becoming available as the arrays primarily erected to measure atmospheric Cherenkov light induced by gamma rays. Planned facilities such as CTA, Cherenkov Telescope Array (www.cta-observatory.org ), envision many tens of telescopes distributed over a few square km. Digital signal handling enables very many baselines to be simultaneously synthesized between many pairs of telescopes, while stars may be tracked across the sky with electronic time delays, in effect synthesizing an optical interferometer in software, enabling two-dimensional imaging with angular resolutions around 30 microarcseconds.

12.03.12 (Monday)
12:00
"Peering into the innermost regions of Eta Carinae and other massive beasts in the Galaxy"
Jose GROH (MPI for Radioastronomy)
Abstract Massive stars are rare but essential constituents of a stellar population. Because these stars have a high luminosity, they lose mass at an enormous rate through stellar winds and episodic giant eruptions during the unstable Luminous Blue Variable (LBV) phase. Shaped by the presence of rapid rotation or a close companion, the circumstellar environment around very massive stars is complex and nothing but spherical. In this talk, I will discuss recent efforts to probe the effects of extreme mass loss, rotation, and binarity in Eta Carinae and its less-famous but extremely interesting siblings. Special emphasis will be given to discuss results from observations that directly resolve spatial scales comparable to those where mass loss originates. I will present how peering into scales as small as a few milli-arcseconds allow us to investigate kinematical effects of rotation and binarity in as much detail as ever.

13.03.12 (Tuesday)
16:00
"Stars outside galaxies"
Duilia DE MELLO (NASA, Catholic University of America, USA)
Abstract I will report the latest results of our project searching for stars born in clusters outside galaxies. Very often, when galaxies collide/merge/interact, their neutral gas, HI, is stripped out of them and found in extended tidal tails in the intergalactic medium. At first glance these gas clouds look empty and even detached from the galaxies. Recently, we have found out that this is not always the case. We used the GALEX ultraviolet satellite to search within HI tails in a sample of interacting galaxies and detected several young stellar clusters and even dwarf galaxies in the process of formation. Our team has analyzed multiwavelength data (Gemini, SDSS, VATT) of these objects showing that they are young and metal rich. Our main conclusion is that they were formed "in situ" from pre-enriched material that was ejected from the galaxies during interaction. These nurseries can be (i) the precursors of globular clusters, (ii) dwarf galaxies in the process of formation or (iii) dissolve and not remain gravitationally bound, yielding only very sparse star streams.
14.03.12 (Wednesday)
16:00
"High and Medium Resolution Transmission Spectroscopy of the Atmospheres of Hot Jupiter Exoplanets - Constraining the Vertical Temperature Structures"
Catherine HUITSON (University of Exeter, UK)
Abstract As a planet passes in front of its host star, light from the star is filtered through the planet's atmosphere, revealing absorption lines characteristic of the atmospheric composition. Our current work uses high and medium resolution transmission spectra of alkali metal lines in the atmospheres of hot Jupiters to understand their physical atmospheric temperature structures. High resolution spectral observations are able to resolve the slope of spectral lines such as sodium and potassium. This slope depends on the temperatures probed by the line, since the atmospheric scale height increases with temperature, causing the line to become more extended at higher temperatures. Comparing model spectral absorption profiles to the data allows us to determine temperatures characteristic of different altitudes, and can be used to determine a profile of temperature versus altitude. If a reference pressure can be determined, this profile also shows us the temperature-pressure (T-P) profile, with higher altitudes corresponding to lower pressures. T-P profiles can be used to constrain atmospheric models, which currently differ significantly from the observations at low pressures. The resulting absorption depths can also be used to constrain elemental abundances. So far, only two exoplanet upper-atmospheric temperature profiles have been measured, both using observations from the HST. We aim to make the first upper-atmospheric temperature profile measurement from the ground using FLAMES on the VLT, which is the purpose of my current visit to Chile. The increased availability of ground-based facilities over space-based facilities mean that successful observations from the ground will greatly increase the number of planets we are able to measure and compare.
16.03.12 (Friday)
12:00
"The ISM of high-redshift galaxies from QSO absorption lines"
Patrick PETITJEAN (IAP, France)
Abstract I will summarize the results of a search for molecular hydrogen and carbon monoxyde in Damped Lyman-alpha systems using UVES and more recently Xshooter. I will show how it is possible to characterize the physical properties of the gas but also to use these detections to constrain cosmology, constraining the temperature of the CMB at high-z or discussing the primordial deuterium abundance.
19.03.12 (Monday)
16:00
"AO Facility"
Robin ARSENAULT (ESO)
Abstract N/A

20.03.12 (Tuesday)
16:00
"The formation and evolution of compact binaries, and their role as gravitational-wave sources"
Marc VAN DER SLUYS (Radboud University Nijmegen, The Netherlands)
Abstract I will present some of our work on the formation and evolution of compact binaries, such as double white dwarfs, AM CVn systems and ultra-compact X-ray binaries. A key moment in the formation of these systems is the so-called common-envelope (CE) phase. The occurrence and outcome of this phase strongly depend on whether mass transfer will be stable or not, on the conservation factor during the stable mass-transfer phase and/or on the binding energy of the donor's envelope. I will also discuss how these compact binaries will be observable by the space-based gravitational-wave (GW) detector LISA, and how the inspiral and merger of compact binaries consisting of neutron stars and/or black holes will (soon) be detected by Advanced LIGO and Virgo. In particular, I will discuss the effect of using knowledge from electromagnetic observations in the GW data analysis.
21.03.12 (Wednesday)
16:00
"Do the Fundamental Constants change with Time?"
Nissim KANEKAR (National Centre for Radio Astrophysics, Tata Institute of Fundamental Research, India)
Abstract Astrophysical spectroscopy in multiple redshifted spectral lines provides a powerful probe of changes in the fine structure constant $\alpha$, the proton g-factor $g_p$ and the proton-electron mass ratio $m_p/m_e$. Under certain astrophysical conditions, a maser mechanism causes the satellite OH 18cm lines to be ``conjugate'', with one line in absorption, the other in emission and the sum of the optical depths consistent with noise. This implies that the lines arise in precisely the same gas, making them ideal transitions through which to study changes in $\alpha$, $\mu$ and $g_p$, with few systematic effects. In this talk, I will present results from deep WSRT, Arecibo and GBT studies of two redshifted conjugate satellite OH systems, at z~0.25 and z~0.77. I will also describe results from an alternative radio technique, comparing redshifts of inversion and rotational transitions, that has yielded the best sensitivity today to changes in the proton-electron mass ratio.

23.03.12 (Friday)
12:00
"Disentangling Streams in the Halo"
Kathy VIVAS (CIDA, Venezuela - Univ. Michigan, USA)
Abstract The halo of the Milky Way is expected to be filled with stellar streams from disrupted dwarf galaxies. The study and characterization of those streams is important to understand the role of mergers in the formation of galaxies like the Milky Way. In the Milky Way's halo there is an important over-density of stars in the region of the constellation of Virgo. Initially interpreted as a single accretion event, today we believe that several different stellar streams lie along the same line of sight. To disentangle the streams in the region we are using kinematic information of RR Lyrae stars from the QUEST survey. Only that kind of stars allow us to have both accurate distances and velocities necessary to differentiate streams in the region.
28.03.12 (Wednesday)
16:00
"New Surprises In Old Stellar Clusters In the history of Astronomy"
Ivo SAVIANE (ESO)
Abstract Galactic Globular clusters have always had an important role in our understanding of stellar evolution and the dynamical evolution of stellar systems. As survivors of the earliest days of the cosmos they also help us understand the formation of the Milky Way and of galaxies in general. In addition they are among the natural test benches for population synthesis models which are then used to interpret unresolved galaxies at high redshift. Advances in instrumentation have recently led to discoveries that have shaken our relatively well-established idea of the nature of these objects. In this framework I will present some of the results that we have obtained recently with several observational studies, with a main focus on the medium-term observational program running at VLT/FORS2. Thanks to these data we have been able to confirm the metallicity dispersion of M54 and M22, and we discovered an object that might be the nuclear cluster of the Cetus Polar Stream.


February

01.02.12 (Wednesday)
16:00
"The SED of Low-Luminosity AGNs at high-spatial resolution"
Juan Antonio ONTIVEROS (MPIfR)
Abstract
02.02.12 (Thursday)
12:00
"Gravitational redshifts, and other wavelength shifts in stellar spectra"
Dainis DRAVINS (Lund University)
PRESENTATION
Abstract
03.02.12 (Friday)
12:00
"On the discovery of a Possible Portrait of Galileo Galilei as a Young Scientist"
Paolo MOLARO (Trieste Observatory)
Abstract
09.02.12 (Thursday)
12:00
"CoRoT transiting exoplanets"
Francois Bouchy (OHP, France)
Abstract
16.02.12 (Thursday)
12:00
"DQ White Dwarfs"
Tommi VORNANEN (University of Turku)
Abstract
16.02.12 (Thursday)
16:00
"A window on planet formation: the case of SDSS J0738+1835"
Patrick DUFOUR (Univ. Montreal)
Abstract
17.02.12 (Friday)
12:00
"The multiplicity of massive stars: implication for stellar evolution"
Hughes SANA (Anton Pannekoek Institute)
Abstract
20.02.12 (Monday)
12:00
"Introduction to astrobiology"
Dainis DRAVINS (Lund University)
PRESENTATION
Abstract
21.02.12 (Tuesday)
12:00
"Revealing the secrets of star-forming galaxies through studies of young stellar clusters"
Angela ADAMO (Stockholm University)
Abstract
22.02.12 (Wednesday)
16:00
"QSO host galaxies"
Roberto DE CARLI (MPIA)
Abstract
23.02.12 (Thursday)
12:00
"The latest SuperWASP results in exoplanet discovery and characterisation"
David ANDERSON (Keele University)
Abstract
24.02.12 (Friday)
12:00
"Star formation in a galaxy structure at z=1.6"
Jaron KURK (MPE)
Abstract
27.02.12 (Monday)
12:00
"The XMM-Newton Bright Ultra-hard Survey"
Silvia MATEOS IBANEZ (IFCA, Spain)
Abstract

28.02.12 (Tuesday)
16:00
"Myths or reality: observing proposal selection at ESO, ALMA and elsewhere"
Gautier MATHYS (ALMA)
Abstract The demand for telescope usage at ESO and in other major observatories often exceeds the available time by large factors, of the order of 3 to 10. In each cycle of proposal selection, the vast majority of the submitted projects are turned down. Understandably, unsuccessful proposers are unhappy. Their attempts to understand the reasons of their failure are hampered by the limited feedback that they receive as well as their lack of knowledge of the proposal review process. They start looking for the "missing link", or worse, the "hidden reason" for their lack of success. Collectively, and over time, this has lead to the build up of a "proposal review lore", in which actual facts and users' conjectures become indistinguishable. I shall present an overview of the current implementation of the proposal selection process at ESO, and sketch its resemblances and differences with the ALMA process, and those of other major observatories. I shall emphasise those aspects that are often questioned by proposers. Finally, I shall give some advice on good practices that should be followed and on pitfalls that should be avoided when preparing an observing proposal.
29.02.12 (Wednesday)
16:00
"Dwarf early-type galaxies and compact stellar systems: differences and
similarities"

Igor CHILINGARIAN (Harvard-Smithsonian Center for Astrophysics)
Abstract I will present recent results on the formation and evolution of low-luminosity early-type galaxies and compact stellar systems. The evolution of these two classes is mostly due to the environment in clusters and groups, however for compact stellar systems the environmental effects are much stronger. (1) Dwarf elliptical galaxies are the numerically dominant type of a galaxy in the local Universe however their origin and evolution still remains a matter of debate. Using modern observational techniques such as optical integral-field spectroscopy, and innovative data analysis, we studied internal kinematics and stellar population properties of a large sample of dwarf elliptical galaxies in nearby clusters and groups. We discovered evolutionary decoupled (usually young and metal-rich) nuclei in many of those systems and kinematically decoupled cores in some of them. These results support the external mechanisms of dE/dS0 formation: ram-pressure stripping and gravitational harassment that cause the late- to early-type galaxy transformation in clusters and groups. (2) Compact stellar systems range in mass from globular clusters to intermediate size galaxies and include ultracompact dwarfs (UCD), compact elliptical galaxies (cE) and some transitional objects. cE galaxies have similar luminosities to dEs, however their structural properties and stellar content are totally different. Being compact, very old and metal-rich, those galaxies most probably originate from intermediate-mass and giant galaxies suffered severe tidal stripping. I will present the discovery of a large number of cE galaxies in nearby clusters and comparison of their properties with the results of numerical simulations. The same physical phenomenon acting on nucleated dE/dS0 galaxies is one of the important channels of UCD formation. I will justify this statement by our recent studies of internal dynamics and stellar population of UCDs in the Fornax and Virgo clusters.


January

 

09.01.12 (Monday)
12:00
"Integrated pupil remapping interferometry with the Dragonfly instrument"
Nemanja JOVANOVIC (Macquarie University, Australia)
Abstract
11.01.12 (Wednesday)
16:00
"The Central Stars of Planetary Nebulae"
Brent MISZALSKI (SAAO/SALT, South Africa)
Abstract
12.01.12 (Thursday)
12:00
"NIR and (sub)mm observations of cometary globules"
Lauri HAIKALA (University of Helsinki)
Abstract
18.01.12 (Wednesday)
16:00
"Be stars: rapidly rotating pulsators"
Thomas RIVINIUS (ESO)
Abstract
20.01.12 (Friday)
12:00
"VISIR upgrade, Why, How, Status"
Hans Ulrich KAEUFL (ESO)
Abstract
25.01.12 (Wednesday)
16:00
"Super-massive Black Holes Across the Cosmic History"
Ezequiel TREISTER (Universidad de Concepcion, Chile)
Abstract
30.01.12 (Monday)
12:00
"Slicing the Monoceros Overdensity"
Blair CONN (MPIA)
Abstract