ESO Santiago Science Colloquia and Seminars 2014

September 2014

4.9.14 (Thursday) Joint ESO-ALMA Colloquium
16:00
"Gas and dust in Galactic Nuclei: nearby Seyfert galaxies and the Galactic Centre"
Marc SCHARTMANN (MPE, Garching)
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"Gas and dust in Galactic Nuclei: nearby Seyfert galaxies and the Galactic Centre"

Marc SCHARTMANN (MPE, Garching)

Abstract

The central engines of Seyfert galaxies are thought to be enshrouded by geometrically thick gas and dust structures. In this talk, I will present continuum radiative transfer simulations of a self-consistent model of such toroidal gas and dust distributions, where the geometrical thickness is achieved and maintained with the help of X-ray heating and radiation pressure due to the central engine. Time-resolved SEDs and images will be compared to available observations, where we find good agreement with observed characteristics especially for those models, which show clear outflow cones in combination with a geometrically thick distribution of gas and dust, as well as a geometrically thin, but high column density disc in the equatorial plane. In the second part of my talk, I will report on the recent developments in monitoring the evolution of the dusty, ionised gas cloud G2 on it's way around the massive black hole in the Galactic Centre, which currently experiences tidal disruption during it's peri centre passage. By using hydrodynamical AMR simulations, we are testing possible origin scenarios and try to predict the observable signature of it's near-future evolution.
5.9.14 (Friday)
12:00
"Exploring intermediate (5-40 AU) scales around AB Aurigae with the Palomar fiber nuller"
Gene SERABYN (JPL)
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"Exploring intermediate (5-40 AU) scales around AB Aurigae with the Palomar fiber nuller"

Gene SERABYN (JPL)

Abstract K-band interferometric observations of the young pre-main sequence star AB Aurigae have been obtained with the Palomar Fiber Nuller (PFN). With a null precision of a few 10-4 inside a field-of-view extending from 35 to 275 mas (5 to 40 AU at AB Aur distance), the PFN is able to explore angular scales intermediate between those accessed by coronagraphic imaging and long baseline interferometry. A mean astrophysical null of 1.52% was detected around AB Aur, with also a slight ±0.2% modulation vs. angle. The isotropic null is indicative of circumstellar emission dominated by an azimuthally extended source, possibly a halo or one or more rings of dust. The modest azimuthal variation may be explained by some skewness or anisotropy of the spatially-extended source, e.g. with an elliptical or spiral geometry, or clumping,or a point-source located at a separation of ~120 mas (17AU) and carrying ~6*10-3 of the stellar flux.

9.9.14 (Tuesday)
12:00
"MOONS: the new multi-object spectrograph for the VLT"
Michele CIRASUOLO (Institute for Astronomy, University of Edinburgh & STFC, UK Astronomy Technology Center)
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"MOONS: the new multi-object spectrograph for the VLT"

Michele CIRASUOLO (Institute for Astronomy, University of Edinburgh & STFC, UK Astronomy Technology Center)

Abstract I will present a science and technical overview of MOONS, the new Multi-Object Optical and Near-infrared Spectrograph, selected by ESO as a third generation instrument for the Very Large Telescope. I will highlight the main science cases and show how MOONS has the observational power needed to unveil galaxy formation and evolution over the entire history of the Universe, from detailed spectroscopy of stars in our Milky Way, to an unprecedented SDSS-like survey at z>1, providing all the crucial follow-up for major facilities like Gaia, VISTA, Euclid etc. Finally, I will present the technical solutions and developments envisaged for MOONS and its overall design.


August 2014

1.8.14 (Friday)
12:00
"Evolution of Science Operations at ESAC"
Bruno ALTIERI (ESA)
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"Evolution of Science Operations at ESAC"

Bruno ALTIERI (ESA)

Abstract

Science operations of ESA astronomy missions started at ESAC in 1978 with the International Ultraviolet Explorer (IUE) . Planetary and solar system missions science operations are also run since more than a decade. From mission planning to Science Data archiving, 25 missions are involved. However the nature and the scope science operations is evolving, and I will show this more particularly with two key ESA mission: the Herschel Space Observatory (2009-2013) which explored the far-infrared and Euclid - to be launched in 2020 - with the aim of constraining the properties of dark matter and dark energy, by surveying 15000 square degrees of the extragalactic sky. ESA-provided elements are usually “embedded” in a larger cooperation with multiple Member State entities on Science Ground Segment. I will address the approaches used to design the structure of the ground segments and the responsibilities of the different sub-entities.
7.8.14 (Thursday)
12:00
"Exploring the magnetic Hertzsprung-Russell diagram with spectropolarimetry : cool stars"
Julien MORIN (Université Montpellier, France)
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"Exploring the magnetic Hertzsprung-Russell diagram with spectropolarimetry : cool stars"

Julien MORIN (Université Montpellier, France)

Abstract

During the past few years, magnetic fields have been detected and studied on stars throughout the Hertzsprung-Russell diagram, and spectropolarimetric techniques have played a key role in this exploration. In this talk I will briefly summarize the theorerical puzzles we want to address in the field of stellar magnetism, discuss issues specific to stellar spectropolarimetry, and present a selection of recent results obtained with spectropolarimetry on cool stars. Finally, I will present how future instruments operating in the near infrared will contribute to the next advances in the field.
8.8.14 (Friday)
12:00
"The B fields in OB stars (BOB) survey"
Swetlana HUBRIG (AIP, Germany)
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"The B fields in OB stars (BOB) survey"

Swetlana HUBRIG (AIP, Germany)

Abstract

Within the B fields in OB stars (BOB) survey, we search for magnetic fields in a sample of OB stars, making use of FORS2 and HARPS. We investigate the frequency of magnetic fields and the distribution of their strengths, ultimately to determine their origin. So far, about 100 objects were observed. Compared to previous surveys, our sample contains mostly slow rotators, providing important clues about the origin of magnetic fields in massive stars.
11.8.14 (Monday)
12:00
"Cold cloud cores and young stellar objects in the Herschel Galactic Cold Cores and Hi-GAL projects"
Sarolta ZAHORECZ (Eotvos University, Budapest, Hungary)
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"Cold cloud cores and young stellar objects in the Herschel Galactic Cold Cores and Hi-GAL projects"

Sarolta ZAHORECZ (Eotvos University, Budapest, Hungary)

Abstract

What are the physical conditions at the earliest stage of star formation? The Planck satellite offered a unique all-sky survey of the coldest clouds in the sky. Based on these Planck data cold clouds were studied with Herschel at higher spatial resolution and a sub-sample also with complementary spectral line data from Effelsberg, APEX, etc. We investigated the star formation properties of these clouds in an unbiased survey as part of the Herschel open time key program "Galactic cold cores". Herschel PACS and SPIRE mapping of the selected cold clouds allowed us to examine the structure and physical characteristics of the sources and their environment. Complementary molecular line measurements confirmed the low temperatures and high densities derived from the FIR data. We made a detailed analysis of associated mid- and far-infrared point sources in the Planck cold clouds. In this talk, I will present the recent and interesting results of our follow-up projects on the Planck cold clumps.
12.8.14 (Tuesday)
12:00
"The intergalactic medium in the cosmic web"
Nicolas TEJOS (University of California,Santa Cruz)
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"The intergalactic medium in the cosmic web"

Nicolas TEJOS (University of California,Santa Cruz)

Abstract

I will present observational results on the properties of the intergalactic medium (IGM) in different environments of the cosmic web. I use proprietary and public data from HST/COS UV spectroscopy of background QSOs to observe the IGM in absorption at z<0.5. By cross-matching the position of individual HI absorption line systems to those of different large scale structures (LSS) traced by galaxy distributions (e.g. voids, filaments, clusters), I characterize the IGM in different cosmic environments. I will present results on the properties of the IGM within and around galaxy voids at z<0.1, that trace low- and mean-density environments respectively. I will also present results on high-density environments, using HST/COS data for a carefully selected QSO sightline that intersects multiple cosmological filaments, traced by galaxy cluster pairs, at z<0.5. With these datasets, we can directly test the modern paradigm for the cosmic web developed from cosmological simulations of structure formation.
13.8.14 (Wednesday)
15:30
"The Millennium Institute for Astrophysics"
Dante MINNITI (Universidad Nacional Andres Bello, Chile)
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"The Millennium Institute for Astrophysics"

Dante MINNITI (Universidad Nacional Andres Bello, Chile)

Abstract

The Millennium Institute for Astrophysics is a new local institution dedicated to Astronomy. I will start by describing its genesis, composition, and overall goals, followed by a general description of the landscape, and some optimistic speculations about the future. The rest of the talk would be dedicated to showing the main activities, concentrating on the ongoing projects and the most recent unpublished scientific results of the VVV Survey.
21.8.14 (Thursday)
15:30
"The Dynamical Evolution of Newborn Stellar Triple Systems"
Bo REIPURTH (University of Hawaii)
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"The Dynamical Evolution of Newborn Stellar Triple Systems"

Bo REIPURTH (University of Hawaii)

Abstract

Recent large surveys have established improved statistics of binarity and multiplicity of embedded low-mass stars, which not only have demonstrated the known excess of binaries among newborn stars, but also have uncovered a surprising excess of wide companions. A new set of extensive numerical N-body simulations of stellar embryos accreting from dense cloud cores have been able to reproduce the main features of the observations, and have uncovered a wide range of dynamical behaviors, which have unexpected connections to various poorly understood phenomena in early stellar evolution, including FUor eruptions and the formation of spectroscopic binaries.
22.8.14 (Friday)
12:00
"The Role of Dwarf Galaxies in the Star Formation History and the Reionization of the Universe"
Hakim ATEK (EPFL, Lausanne)
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"The Role of Dwarf Galaxies in the Star Formation History and the Reionization of the Universe"

Hakim ATEK (EPFL, Lausanne)

Abstract

Understanding the formation and evolution of galaxies is one of the foremost challenges in modern astrophysics. We are only beginning to unravel the complex interplay of key processes that include galaxy mergers, gas inflow, and feedback driven by supernovae and AGN. Yet, much of our empirical knowledge of galaxy evolution is biased by the way samples are selected (e.g. magnitude limits, dust obscuration). I will present recent results from HST slitless spectroscopy observations that provide unbiased measures of galaxy evolution to very faint continuum magnitudes. I will focus in particular on a population of dwarf galaxies at z=1-2 with extremely strong emission lines and their implications on galaxy evolution and high-redshift studies. The contribution of this population to the total star formation density might be more important than expected. I will then show how the gravitational lensing of massive galaxy clusters can give access to the faintest dwarf galaxies at high redshift. We will see the latest results from the Hubble Frontier Fields program investigating the contribution of dwarf galaxies to the cosmic reionization.
26.8.14 (Tuesday)
12:00
"Atomic Data Calculations at Queen's University Belfast"
Kanti M. AGGARWAL (Queen's University Belfast)
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"Atomic Data Calculations at Queen's University Belfast"

Kanti M. AGGARWAL (Queen's University Belfast)

Abstract

In this seminar atomic data (namely energy levels, radiative rates, life-times, electron impact excitation collision strengths, and rate coefficients) will be discussed for a variety of ions, which have applications in modelling and diagnostics of solar and other astrophysical plasmas. These results are theoretical from the fully relativistic GRASP (General purpose Relativistic Atomic Structure Package) and DARC (Dirac Atomic R-matrix Code) programs. The difficulties of performing large calculations, and importance of including relativistic effects and resonances in the determination of excitation rates will be highlighted. Comparisons will be shown and discrepancies with other available data will be discussed. Results will specifically be presented from our recent calculations on Al X, Si II and Fe XIV. The difficulties of assessing the accuracy of atomic data will also be emphasized.
28.8.14 (Thursday)
12:00
"Characterization of debris disk in direct imaging and high angular resolution"
Julien MILLI (ESO, Chile)
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"Characterization of debris disk in direct imaging and high angular resolution"

Julien MILLI (ESO, Chile)

Abstract

To shed light on the formation and evolution of planetary systems, I will present an observational approach based on the study of debris discs. These circumstellar discs are composed of dust particles constantly generated by collisions of small rocky bodies called planetesimals, orbiting a main-sequence star. The stellar light they scatter can be studied from the Earth and reveal a wealth of information on the architecture of the system. These observations are challenging because of the high contrast and the small angular separation between the disc and the star. The recent developments of new high-contrast instruments with extreme adaptive optic systems are therefore bringing new expectations for the study of these systems. In this talk, I will present the characterization of two debris discs thanks to two instruments installed on the Very Large Telescope: NaCo and SPHERE (Spectro Polarimetric High contrast Exoplanet REsearch). NaCo has been in operation for more than a decade and has undergone many improvements. SPHERE has been designed and assembled in the same period, was intensively tested in laboratory in 2013, and is currently being commissioned on the telescope. In the first part, I show why a detailed understanding of the behaviour of the instrument is crucial to detect and characterize disks in scattered light. I quantify in particular the performances, advantages, and biases of the angular, polarimetric and reference-star differential imaging technique. In a next step, I apply those techniques to characterize two prototypes of debris discs, around the stars β Pictoris and HR 4796A. A detailed analysis of the morphology is carried out, which reveals new asymmetries interpreted in terms of gravitational perturbers or of dust scattering properties.

July 2014

3.7.14 (Thursday)
12:00
"DANCe: complementing Gaia from the ground and preparing for LSST"
Herve BOUY (Centro de Astrobiologia, Madrid)
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"DANCe: complementing Gaia from the ground and preparing for LSST"

Herve BOUY (Centro de Astrobiologia, Madrid)

Abstract

The DANCe projects is a wide field ground-based survey of young nearby associations and clusters meant to prepare and complement the Gaia mission and LSST survey. Taking advantage of the numerous wide field public archives, we derive precise proper motions and multi-wavelength photometry over several tens of square degrees in young (<600Myr) nearby (<500pc) associations. Our new advanced data processing and astrometric pipelines allow us to reach an accuracy of 0.3 mas/yr (best case) up to i~23mag, thus ~4 mag deeper than Gaia, and comparable to the expected LSST accuracy and sensitivity. To analyse the million-source catalogues produced by DANCe, we are also developing novel statistical methods based on advanced multi-dimensional probabilistic analysis to derive reliable membership probabilities. In the case of the Pleiades cluster, the survey leads to approx. 1650 high confidence (probability>75%) members, or twice the most recent census (dated 2012). The experience acquired with the DANCe project, both for the astrometric and sub-sequent scientific analysis, could be very valuable for the future Gaia and LSST surveys. While our interests are focused on young nearby clusters, the scientific applications are countless, including for example TNO, galactic populations, brown dwarfs, white dwarfs, etc... Our website: http://www.project-dance.com
9.7.14 (Wednesday)
14:00
"Dust depletion in the Galactic and extragalactic ISM"
Annalisa DE CIA (The Weizmann Institute of Science, Rehovot, Israel)
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"Dust depletion in the Galactic and extragalactic ISM"

Annalisa DE CIA (The Weizmann Institute of Science, Rehovot, Israel)

Abstract

The observation of the relative abundances in the interstellar medium and the study of the depletion of metals in dust grains has provided important clues to the properties of Galactic and extragalactic dust. I will review the current status of dust-depletion studies in the Galaxy, QSO- and GRB-DLAs, and discuss the most recent results.

June 2014

4.6.14 (Wednesday)
15:30
"Origin of the magnetic fields in neutron stars"
Henk SPRUIT (MPA, Garching)
Abstract
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"Origin of the magnetic fields in neutron stars"

Henk SPRUIT (MPA, Garching)

Abstract

The (dipole component of the) field strengths inferred for pulsars and magnetars range over a factor 100000, from about 10^10 G to 10^15 G. What does this mean: is this large range somehow a property of one single formation mechanism, or do we have to invoke several different mechanisms for different values of the field strength ? The talk will review the different possible origins that have been proposed for neutron star magnetic fields against the background of this question. Field generation during and shortly after collapse of the pre-SN core is tentatively identified as the most probable answer.
5.6.14 (Thursday)
12:00
"Planetary nebula Hen 2-260 and its variable central star"
Marcin HAJDUK (Nicolaus Copernicus University, Toruń)
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"Planetary nebula Hen 2-260 and its variable central star"

Marcin HAJDUK (Nicolaus Copernicus University, Toruń)

Abstract

We discovered the central star of the planetary nebula Hen 2-260 to be variable. The photometric monitoring of Hen 2-260 revealed non-periodic variations on a timescale of hours or days. There is no direct indication for the central star binarity in the spectrum nor for strong stellar wind. Variability is most likely caused by the pulsations of the star. The nebula is relatively dense and young. The central star is at the point to start O+ ionization (Teff ?= 30000K). We report the 50% increase of the [OIII] 5007A line flux between 2001 and 2012. The central star evolves to higher temperatures at the rate of (38 ± 7) K yr−1, consistent with the post-AGB evolutionary tracks for the final mass of about 0.63Msun.
11.6.14 (Wednesday)
15:30
"A starburst region near the far end of the Long Galactic Bar"
Ignacio NEGUERUELA (Universidad de Alicante)
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"A starburst region near the far end of the Long Galactic Bar"

Ignacio NEGUERUELA (Universidad de Alicante)

Abstract

In recent years, strong evidence for starburst-like star formation close to the base of the Scutum arm has emerged. The birth of several massive young clusters and a spatially-extended associated population of red supergiants is thought to have been triggered by the interaction of the Long Galactic Bar, whose near tip is found along this line of sight, with the spiral arm. If this view is correct, the opposite side of the Bar should be giving rise to similarly vigorous star formation. Unfortunately, the location of the far end of the Galactic Bar is unsure, with different models making quite diverse predictions. I will report on the identification of two clusters of red supergiants towards galactic longitude 350 deg, with kinematic and photometric distances from the Sun around 10 kpc. One of the clusters is likely to have a mass above 20000 Msun, based on the presence of a large number of blue and red supergiants. The other cluster is surrounded by a large number of red supergiants with identical radial velocity, pointing to the existence of a rather extended star-forming region that could mirror the Scutum arm Complex. The clusters are seen through a gap in the extinction that will allow for an accurate determination of the extinction law towards the inner Milky Way.
12.6.14 (Thursday)
12:00
"HST/STIS Transmission Spectral Survey: Probing the Atmospheres of HAT-P-1b and WASP-6b"
Nikolay NIKOLOV (University of Exeter)
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"HST/STIS Transmission Spectral Survey: Probing the Atmospheres of HAT-P-1b and WASP-6b"

Nikolay NIKOLOV (University of Exeter)

Abstract

We present optical to near-infrared transmission spectra of HAT-P-1b and WASP-6b, part of a Large HST/STIS hot Jupiter transmission spectral survey (P.I. David Sing). The spectra for each target cover the regimes 2900−5700Å and 5240−10270Å, with resolving power of R = 500. The HAT-P-1b data is coupled with a recent HST/WFC3 transit, spanning the wavelength range 1.087-1.687microns (R=130), acquired in spatial scan mode. The WASP-6b data is complemented with Spritzer/IRAC 3.6 and 4.5 micron transit observations, part of a comparative exoplanetology program (P.I. Jean-Michel Desert). The transmission spectrum of HAT-P-1b shows a strong absorption signature shortward of 5500Å, with a strong blueward slope into the near-UV. We detect atmospheric sodium absorption at a 3.3σ significance level, but see no evidence for the potassium feature. The red data implies a marginally flat spectrum with a tentative absorption enhancement at wavelength longer than ~8500Å. The combined STIS and WFC3 optical to NIR spectra differ significantly in absolute radius level (4.3+/-1.6 pressure scale heights), implying strong optical absorption in the atmosphere of HAT-P-1b. The optical to near-infrared difference cannot be explained by stellar activity, as simultaneous stellar activity monitoring of the G0V HAT-P-1b host star and its identical companion show no significant activity that could explain the result. The transmission spectrum of WASP-6b shows evidence for strong Daylight scattering with tentative detection of sodium (~1σ) and potassium (~2σ). We compare both spectra with theoretical models including cloud-free, haze dominated and models with extra optical absorbers. We find that both an optical absorber and a super-solar sodium to water abundance ratio might be a scenario explaining the HAT-P-1b observations. Both Rayleigh scattering and a cloud deck in the optical might be possible scenarios for the atmosphere of WASP-6b. Our results suggest that strong optical absorbers/hazes may be a dominant atmospheric features shaping the transmission spectra in some hot Jupiter exoplanets.
16.6.14 (Monday)
15:30
"*Athena*: The X-ray observatory to study the hot and energetic Universe"
Xavier BARCONS (IFCA)
Abstract
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"*Athena*: The X-ray observatory to study the hot and energetic Universe"

Xavier BARCONS (IFCA)

Abstract

Hot gas pervades the Universe: about half of the baryonic content in the Universe is expected to be at T>10^5 K, and there are as many baryons at T>10^7 trapped in galaxy clusters as there are locked into stars. There is an intimate relation between this hot gas, which delineates the large-scale structure of the Universe, and the most energetic phenomena occurring in the immediate vicinity of black holes. The link between both has been dubbed Cosmic Feedback, whereby the growth of supermassive black holes regulates star formation and shapes galaxies. Studying the Hot and Energetic Universe requires X-ray observatories in space, whose capabilities greatly exceed those of the current workhorse observatories: NASA's *Chandra* and ESA's *XMM-Newton*. ESA will launch a large X-ray observatory mission in 2028 to address the above topics. *Athena* (Advanced Telescope for High Energy Astrophysics) is the mission concept put forward to meet those and other equally key science goals for contemporary astrophysics. In this talk, I will describe the *Athena* science objectives, the mission concept, the X-ray telescope and its two baseline instruments: a Wide Field Imager (WFI) and an X-ray Integral Field Unit (X-IFU).
18.6.14 (Wednesday)
12:00
"Detailed physical modeling of a classical Be star beta CMi"
Robert KLEMENT (Astronomical Inst., Charles University, Prague, Czech Republic & ESO, Chile)
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"Detailed physical modeling of a classical Be star beta CMi"

Robert KLEMENT (Astronomical Inst., Charles University, Prague, Czech Republic & ESO, Chile)

Abstract

Be stars are rapidly rotating stars with circumstellar envelopes in the form of equatorial disks. The close and bright B8Ve star beta CMi represents a perfect laboratory to study the detailed structure of a stable, unperturbed disk which is not truncated by a close binary companion. The NLTE Monte Carlo radiative transfer code HDUST is used to model the SED from UV up to cm wavelengths along with visual spectroscopy, polarimetry and near-IR interferometry. Special focus is put on testing the viscous decretion disk (VDD) scenario in the outer parts of the disk, which are observed in the far-IR and radio wavelengths. With the available data we are able to put constrains on the physical extent of the disk for the first time.

May 2014

7.5.14 (Wednesday)
12:00
"Exploring and exploiting the diversity of exoplanetary systems"
Amaury TRIAUD (MIT Kavli Inst. for Astrophysics and Space Research, USA)
Abstract
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"Exploring and exploiting the diversity of exoplanetary systems"

Amaury TRIAUD (MIT Kavli Inst. for Astrophysics and Space Research, USA)

Abstract

From the first discoveries and over 20 years of search we have uncovered that exoplanets present a wide variety in every parameter we can measure. This notably shows that our Solar system did not participate in the dominant planet formation and evolution mechanism in the Galaxy. I will show results from the Rossiter-McLaughlin effect showing that some systems do not occupy orbits coplanar with their star. Building on that knowledge I will explore how inclined planets behave when orbiting close binary stars and reveal that many of them could be found transiting within the Kepler data with interesting consequences on the rates of discovery. Finally, I will expand our knowledge on the diversity of systems to realms not yet explored with the aim to increase our odds of finding but also of studying habitable planets.
8.5.14 (Thursday)
12:00
"Probing the formation of bulges in disc galaxies"
Sonali SACHDEVA (University of Delhi, India and ESO, Chile)
Abstract
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"Probing the formation of bulges in disc galaxies"

Sonali SACHDEVA (University of Delhi, India and ESO, Chile)

Abstract

The presence of a large number of bulgeless or pure-disc galaxies in the universe challenges the LCDM model of galaxy-formation. We have studied their luminosity and size evolution in comparison to disc-galaxies with bulges upto z~1. Our results strongly suggest that a fraction of the bulgeless galaxy population might be acquiring a bulge with time. We are currently trying to ascertain this conjecture. To that end, we have computed the concentration, asymmetry and clumpiness parameters for our sample of 567 disc-galaxies, obtained from HST and SDSS, both with and without bulges, at three redshift-bins. In this talk, I will share some of our recent findings.
9.5.14 (Friday)
14:00
"Cosmology with the Microwave Background Radiation"
Anthony READHEAD (Caltech, USA)
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"Cosmology with the Microwave Background Radiation"

Anthony READHEAD (Caltech, USA)

Abstract

In the field of cosmic microwave background observations small groups can do fundamental experiments with modest instruments. The development of this field will be described, including three key B-Mode experiments carried out on the Llano de Chajnantor - the Cosmic Background Imager and the QUIET Q and QUIET W experiments - up to the latest results of the Planck satellite and those of the BICEP2 experiment, which if confirmed push the cosmic clock back to 10-38 seconds after the Big Bang; and the future of experimental radio astronomy in the era of mega-projects (ALMA and the SKA) will be discussed in the light of the current renaissance in low frequency experimental radio astronomy.
23.5.14 (Friday)
12:00
"Exoplanets & Astrobiology -- the spectroscopic search for life on other worlds"
Daniel ANGERHAUSEN (Rensselaer Polytechnic Institute, NY, USA)
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"Exoplanets & Astrobiology -- the spectroscopic search for life on other worlds"

Daniel ANGERHAUSEN (Rensselaer Polytechnic Institute, NY, USA)

Abstract

In my presentation I will give a short introduction to the science of extrasolar planets, in particular the technique of transit spectro-photometry. I will describe my various projects in this emerging field using state of the art spectroscopic and photometric instruments on the largest ground based telescopes, the 'flying telescope' SOFIA (Stratospheric Observatory for Infrared Astronomy) and the Kepler and Hubble space telescopes. I will connect this science case to the broader field of Astrobiology and the prospects of detecting biomarkers in the future.
28.5.14 (Wednesday)
15:30
"Small-scale structure in the diffuse interstellar medium"
Keith SMITH (Assistant Editor, MNRAS)
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"Small-scale structure in the diffuse interstellar medium"

Keith SMITH (Assistant Editor, MNRAS)

Abstract

I will review the discovery of significant structure in the diffuse interstellar medium (ISM) on scales down to ~10 AU (10^-4 pc). This contradicts standard theories of the ISM, which indicate that it should be homogeneous on scales below about a parsec. Evidence will be presented from observations of the ISM at UV, optical, far-IR and radio wavelengths. I will conclude by examining two competing interpretations: fluctuations in ionisation, or fluctuations in density.
29.5.14 (Thursday)
12:00
"One thousand cataclysmic variables from the Catalina Real-time Transient Survey"
Elmé BREEDT (University of Warwick)
Abstract
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"Small-scale structure in the diffuse interstellar medium"

Elmé BREEDT (University of Warwick)

Abstract

Cataclysmic variables (CVs) are the dominant population of interacting compact binaries, and their study is key to improve our understanding of accretion physics and the evolution of close binaries. Thanks to their highly variable and eruptive nature, CVs are easily identified in transient surveys. My current work is based on the Catalina Real-time Transient Survey (CRTS), which has identified a catalogue of more than 1000 cataclysmic variables in its first six years of operation, the majority of which were new discoveries. I will present the highlights from our spectroscopic follow-up program, and an analysis of the discovery rate and outburst distribution of the CRTS CVs. I will show that the sample contains a large fraction of low accretion rate WZ Sge type CVs, but that many more remain to be discovered.

April 2014

16.4.14 (Wednesday)
15:30
"IP Eri and the formation of long-period eccentric binaries with a helium white dwarf"
Lionel SIESS (Universite Libre de Bruxelles, Belgium)
Abstract
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"IP Eri and the formation of long-period eccentric binaries with a helium white dwarf"

Lionel SIESS (Universite Libre de Bruxelles, Belgium)

Abstract

The recent discovery of long-period eccentric binaries hosting a He-WD or a sdB star has been challenging binary-star modelling. Based on accurate determinations of the stellar and orbital parameters for IP Eri, a K0 + He-WD system, we propose an evolutionary path that is able to explain the observational properties of this system and, in particular, to account for its high eccentricity (0.25). Our scenario invokes an enhanced-wind mass loss on the first red giant branch (RGB) in order to avoid mass transfer by Roche-lobe overflow, where tides systematically circularize the orbit. We explore how the evolution of the orbital parameters depends on the initial conditions and show that eccentricity can be preserved and even increased if the initial separation is large enough. The low spin velocity of the K0 giant implies that accretion of angular momentum from a (tidally-enhanced) RGB wind should not be efficient.
23.4.14 (Wednesday)
15:30
"Periodic variable stars of type A and B"
Nami MOWLAVI (University of Geneva, Switzerland)
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"Periodic variable stars of type A and B"

Nami MOWLAVI (University of Geneva, Switzerland)

Abstract

The talk is centered on the discovery of a new class of main sequence periodic variable stars, located in the Hertzsprung-Russell diagram in the region between delta-Scuti and Slowly Pulsating B stars. I will present their discovery and discuss their possible origin.
24.4.14 (Thursday)
12:00
"The puzzling origin of magnetism in higher-mass stars"
Jason GRUNHUT (ESO Garching)
Abstract
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"The puzzling origin of magnetism in higher-mass stars"

Jason GRUNHUT (ESO Garching)

Abstract

The presence of magnetic fields in a small subset of main sequence intermediate-mass (A and late B-type) stars has been well-known for over 60 years. In the last 10 years, a new generation of spectropolarimeters has furthered our knowledge with the systematic discovery of magnetic fields among the pre-main sequence progenitors of the A and B-type stars (the Herbig Ae/Be stars) and among high-mass stars (main sequence early B and O-type stars). It is now well-established that ~10% of all stars with radiative envelopes (spanning ~1.5 decades of mass and at different evolutionary phases) host strong (surface polar field strengths of ~1 kG), stable (on the order of at least decades), globally-order (mainly dipolar) magnetic fields despite the fact that these stars lack a significant convective envelope - a key ingredient in driving any contemporaneous dynamo that is believed to be responsible for generating magnetic fields in a large range of astrophysical objects. Despite all our knowledge about magnetism in these stars, the fundamental question regarding the origin of their magnetic fields is still highly debated. In this talk I will discuss several theories that endeavour to explain the origin of magnetism in these stars and the observational evidence that may or may not support these ideas, including preliminary results from several ongoing programs that try to address this fundamental question.
30.4.14 (Wednesday)
12:00
"Solving the puzzles of Milky Way"
Pawel PIETRUKOWICZ (Obserwatorium Astronomiczne Uniwersytetu Warszawskiego)
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"Solving the puzzles of Milky Way"

Pawel PIETRUKOWICZ (Obserwatorium Astronomiczne Uniwersytetu Warszawskiego)

Abstract

Our location among billions of stars of our disky Galaxy makes the studies on its structure and evolution extremely difficult. Ongoing large-scale optical and infrared galaxy surveys, such as OGLE and VVV, are on a good way to find answers to key questions.

March 2014

5.3.14 (Wednesday)
15:30
"Large scale correlations of quasar polarization vectors: hints of extreme scale structures or evidence for axion-like particles?"
Damien HUTSEMÉKERS (Astrophysics Institute, University of Liege, Belgium)
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"Large scale correlations of quasar polarization vectors: hints of extreme scale structures or evidence for axion-like particles?"

Damien HUTSEMÉKERS (Astrophysics Institute, University of Liege, Belgium)

Abstract

Based on a sample of 355 quasars with significant optical linear polarization and using various statistical methods, we show that quasar polarization vectors are not randomly oriented over the sky with a probability often in excess of 99.9%. The polarization vectors appear coherently aligned over huge regions of the sky (~1 Gpc), located at both low (z ~0.5) and high (z ~1.5) redshifts and characterized by different preferred directions of the polarization. These characteristics make the alignment effect difficult to explain in terms of contamination by instrumental or interstellar polarization in our Galaxy. We notice that the region of the sky where the alignments are prominent is not far from preferred directions tentatively identified in the Cosmic Microwave Background. Polarization alignments may thus reveal structures at scales beyond the homogeneity scale of concordance cosmology. Several interpretations are discussed. In particular, we show that the dichroism and birefringence predicted by photon pseudo-scalar oscillation along the line of sight cannot reproduce the observed properties of the alignments. Besides, accurate measurements of quasar circular polarization allow us to strongly constrain the parameter space of axion-like particles.
11.3.14 (Tuesday)
12:00
"A dynamical study of the open star cluster NGC 2287"
Anna SIPPEL (ESO, Chile)
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"A dynamical study of the open star cluster NGC 2287"

Anna SIPPEL (ESO, Chile)

Abstract

Estimating open cluster masses using photometry can lead to different results depending on the method used. To understand which approach leads to more accuarate results, we use multi-epoch FLAMES spectroscopy to calculate the dynamical mass -- an independent mass estimate. With the ultimate goal of understanding if open clusters have a chance to survive or are born to disperse, I will present the preliminary results of this pilot study and my project here at ESO.
20.3.14 (Thursday)
12:00
"Probing the inner structure of quasar using gravitational microlensing"
Lorraine BRAIBANT (Universite de Liege, Belgium)
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"Probing the inner structure of quasar using gravitational microlensing"

Lorraine BRAIBANT (Universite de Liege, Belgium)

Abstract

Gravitational microlensing is a powerful tool which allows astronomers to study the most inner parts of QSO that can’t be spatially resolved by current telescopes. Indeed, stellar-mass objects contained in the lensing galaxy can typically substantially magnify regions of the source plane on scales of a few nano- or micro-arcseconds, which interestingly correspond to the size of QSO unresolved inner regions. Among other things, microlensing can give rise to spectral differences between the multiple images of a same background quasar which constitute a cosmic mirage. A lot of information about the physical properties of the accretion disk and the geometry of the broad line region can be retrieved from these spectral differences. (e.g., Hutsemékers et al., 2010, Sluse et al., 2012). Using the decomposition method described in Sluse et al. (2007) and Hutsemékers et al. (2010), which allows to disentangle the part of the quasar spectrum affected by microlensing, we have studied three quadruple gravitational lenses which are known or suspected to be affected by microlensing: H1413+117, HE0435-1223 and PG1115+080.
27.3.14 (Thursday)
12:00
"As the Dust Settles: using time-domain observations to reveal cloud structure in substellar atmospheres"
Jackie RADIGAN (STScI,USA)
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"As the Dust Settles: using time-domain observations to reveal cloud structure in substellar atmospheres"

Jackie RADIGAN (STScI,USA)

Abstract

The combination of condensate clouds and rapid rotation has long motivated searches for weather phenomena in ultracool (late-M, L and T) dwarf (UCD) atmospheres. Pioneering work in this field dating back as early as 1999 suggested that variability is quite common for UCDs. Yet these early studies were ambiguous: detections were often low-amplitude and/or lacking periodicity, and the mechanisms responsible remained unclear. Observations made in the past 5 years, utilizing continuous monitoring strategies, better instruments, and larger telescopes have demonstrated conclusive and surprisingly large near-infrared variability for a subset of brown dwarfs at the transition between L and T spectral types, suggesting a patchy distribution of silicate clouds in their atmospheres. Brightness variations as large as 25% on readily observable rotational timescales allow light curves of exquisite precision, worthy of detailed analysis, to be obtained from both ground and space based facilities. While the L/T transition is the realm of spectacular variability, recent space-based efforts have confirmed lower levels of variability for a substantial fraction of UCDs at all spectral types. I will describe how such multi-wavelength, multi-epoch observations are contributing to an emerging picture of cloud structure in brown dwarf and exoplanet atmospheres.
31.3.14 (Monday)
12:00
"Systemic mass loss in interacting binaries: Can we reconcile binary star models with observations?"
Romain DESCHAMPS (ESO, Chile)
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"Systemic mass loss in interacting binaries: Can we reconcile binary star models with observations?"

Romain DESCHAMPS (ESO, Chile)

Abstract

Systemic mass loss in interacting binaries such as of the Algol-type has been inferred since the 50s. There is indeed gathering indirect evidence indicating that some Algols follow non-conservative evolutions but still no direct detection of large mass outflows. As a result, little is known about the eventual ejection mechanism. In order to reconcile stellar models with observations, we compute typical Algol models with the state-of-the-art binary star evolution code Binstar. We investigate systemic mass losses within the hotspot paradigm where large outflows of material forms from the accretion impact during the mass transfer phase. We then study the impact of this outflow on the spectral emission distribution of the system with the radiative transfer codes Cloudy and Skirt.

February 2014

6.2.14 (Thursday)
15:30
"Physics of Star Formation"
Thomas HENNING (Max Planck Institute for Astronomy, Heidelberg)
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"Physics of Star Formation"

Thomas HENNING (Max Planck Institute for Astronomy, Heidelberg)

Abstract

Star formation is a fundamental process in the universe, shaping the structure of our and other galaxies. The birth of stars is triggered by the gravitational collapse and fragmentation of cold molecular clouds. The talk will summarize the general physical principles of the star formation process. It will discuss global properties such as the star formation efficiency and the initial mass function. In addition, it will also demonstrate the power of adaptive optics in revealing the structure of star-forming regions and will show new exciting results obtained with the Herschel Space Observatory.
27.2.14 (Thursday)
12:00
"The metallicity of the z~2.5 circumgalactic medium"
Neil CRIGHTON (Swinburne University of Technology)
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"The metallicity of the z~2.5 circumgalactic medium"

Neil CRIGHTON (Swinburne University of Technology)

Abstract

Observations of the gaseous halos of galaxies (the circumgalactic medium or CGM) are able to constrain important but poorly-understood mechanisms that govern galaxy formation, such as supernovae-driven outflows and gas inflowing along cold-accretion streams. I will present the first results from our group's survey of cool gas in the CGM of galaxies at z~2.5, near the peak of the cosmic star formation rate. By comparing the gas absorption features seen towards a background QSO sightline nearby a foreground galaxy to photo-ionization models we measure the metallicity of the CGM gas, which is crucial to determine its origin. We introduce a new method of measuring the gas metallicity that incorporates variations in the shape of the UV radiation field illuminating the gas, resulting in robust metallicity uncertainties. We apply this method to a galaxy-absorber pair discovered by our survey, and show that metal-enriched gas exists in the galaxy's halo out to a minimum radius of ~50 kpc.

January 2014

7.1.14 (Tuesday)
12:00
"The origin of hot subdwarf stars"
Roy ØSTENSEN (Leuven University, Belgium)
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"The origin of hot subdwarf stars"

Roy ØSTENSEN (Leuven University, Belgium)

Abstract

Hot subdwarf stars are the remnants of stars that have somehow lost their hydrogen envelope during the red giant phase, and are now core-helium burning without a hydrogen burning shell. In order to reach this peculiar configuration they must have lost almost all their remaining hydrogen in some kind of binary interaction. The majority of such subdwarfs are found in binary systems, but a significant number appears to be devoid of any companions that can have caused such significant mass loss. I discuss the latest results with respect to the binary connections and the asteroseismic results revealed by data from the Kepler spacecraft, and outline the tentative connections for giant planets to be involved in the envelope ejection.
10.1.14 (Friday)
12:00
"Is Mars Alive?"
Geronimo VILLANUEVA (NASA-GSFC/CUA, Greenbelt, MD)
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"Is Mars Alive?"

Geronimo VILLANUEVA (NASA-GSFC/CUA, Greenbelt, MD)

Abstract

Is there any biological or geological activity currently on Mars? Is Mars currently habitable or has ever been so? We are much closer to answer these fundamental questions than ever before, thanks to the astronomical power of telescopes such as VLT, Keck and NASA-IRTF. We have obtained extremely detailed spectra of Mars for the last 10 years using these three observatories, leading to the most comprehensive spectral database targeting trace species on Mars ever acquired. Our measurements include the search for methane, a biomarker on Earth, and of water, including several of its isotopes.These astronomical results will be contrasted with the measurements obtained by NASA’s Curiosity rover, which is now exploring the Gale Crater with the most powerful suite of instruments ever to reach the surface of Mars.
13.1.14 (Monday)
15:30
"The GRBs Afterglow: ESO Key Role"
Guido CHINCARINI (Università degli Studi di Milano)
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"The GRBs Afterglow: ESO Key Role"

Guido CHINCARINI (Università degli Studi di Milano)

Abstract

After a brief introduction I review some of the highlights of the GRBs afterglow evidencing the observations obtained using the ESO facilities. With the discovery that also short GRBs are extragalactic we got a reasonable understanding of the energy and the likely progenitor identified as a NS+NS merging. This leads to the need of demonstrating it via gravitational waves detection. Long GRBs show evidence of early (prompt emission) variability all over the electromagnetic spectrum and the effect the radiation has on the Interstellar Medium. This call for high speed pointing capability telescopes. One of the strongest clue for modeling the collapse is the connection GRBs ­ SNe. ESO did an excellent work observing all events with z <0.2. Long GRBs have been detected at high redshifts so that GRBs may be a way to better understand the Cosmic Star Formation Rate (CSFR) that is poorly understood at high z. One of the main tasks for the future will be the understanding of GRBs magnetic fields, their formation and related particle acceleration.
15.1.14 (Wednesday)
15:30
"The Venus Transit of 2012 & other Transits"
Paolo MOLARO (Osservatorio Astronomico di Trieste)
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"The Venus Transit of 2012 & other Transits"

Paolo MOLARO (Osservatorio Astronomico di Trieste)

Abstract

Since antiquity the transit of planets, or their absence, have been important in the construction of the Heavens. The Transit of Venus foreseen by Kepler provided an important argument in favor of the Copernican model and allowed a precise measurement of the dimensions of the solar system. The study of the transit of exoplanets is an important technique in the study of their physical properties and therefore we exploited scientifically the Venus Transit of 6th June 2012. By using the Moon as a reflector of the solar light we have detected the Rossiter MacLaughlin effect produced by Venus transiting the solar disk. With this detection we showed that it is possible to detect a very small RM effect against the stellar jitter. This technique showed also that it is possible to measure small variations of the photospheric solar lines at the m/s level. A novel solar atlas based on Laser Frequency Comb will be presented along with some possible applications. The recent observations of the Earth transit in front of the solar disk as seen from Jupiter on the 5th January 2014 will be also mentioned.
16.1.14 (Thursday)
12:00
"The Multi Unit Spectroscopic Explorer MUSE for the VLT"
Roland BACON (Observatoire de Lyon, France)
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"The Multi Unit Spectroscopic Explorer MUSE for the VLT"

Roland BACON (Observatoire de Lyon, France)

Abstract

The 2nd generation VLT instrument MUSE is now in Paranal and commissioning will start in a few days. I will present this innovative instrument, its expected performances and its science prospect, with an emphasis on the field of galaxy formation and evolution.
21.1.14 (Tuesday)
12:00
"230 years of AGN monitoring: Frequency of cloud occultation events in AGN & constraints for clumpy torus models"
Mirko KRUMPE (ESO, Garching)
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"230 years of AGN monitoring: Frequency of cloud occultation events in AGN & constraints for clumpy torus models"

Mirko KRUMPE (ESO, Garching)

Abstract

We systematically search for discrete absorption events in the vast archive of the Rossi X-ray Timing Explorer. This includes dozens of nearby type I and Compton-thin type II AGN and covers timescales from days to over a decade for individual objects. We are sensitive to discrete absorption events due to clouds of full-covering, neutral or mildly-ionized gas with columns 1022-25 cm-2 transiting the line of sight. We detect 13 eclipse events in 8 objects, roughly tripling the number of previously published events from this archive. Despite sensitivity to events with NH up to 1024-25 cm-2, we measured no Compton-thick eclipses in our sample. Peak column densities span 2.5 - 19 x 1022 cm-2. Event durations span hours to months. We infer the clouds’ distances from the black hole, assuming Keplerian motion, to span 0. 2 - 80 x 104 Schwarzschild radii. We find no statistically significant difference between the individual cloud properties of type I and II objects. The presence of eclipses in both type Is and IIs argues against sharp-edged cloud distributions. The type II AGN show a level of “base-line” X-ray absorption that is consistent with being constant over timescales from 0.6 to 8.4 yr. This can either be explained by a homogeneous medium, or by X-ray-absorbing clouds that each have NH << 1022 cm-2. Considering the "selection function" of the monitoring, we derive the probability of cloud occultation events. Finally, we derive the first X-ray statistical constraints for clumpy-torus models.
27.1.14 (Monday)
12:00
"What can stellar magnetic field tell us about exoplanetary systems?"
Rim FARES (University of St Andrews, School of Physics & Astronomy)
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"What can stellar magnetic field tell us about exoplanetary systems?"

Rim FARES (University of St Andrews, School of Physics & Astronomy)

Abstract

Extrasolar planets at small orbital distances (hot Jupiters) interact with their hosting star in several ways: irradiation, gravitation, flow of particles and magnetic fields. The planet, embedded in the large-scale stellar magnetic field throughout its orbit, can influence the star in the form of induced photospheric activity, or by influencing the stellar magnetic field via tidal interactions. Studying the stellar magnetic field can give us insights on the interactions in these systems.
I will present my work on the study of the magnetic field of a sample of hot-Jupiter hosting stars and show how the properties of their magnetic field compare to cool stars with no hot-Jupiter. We observed the first large-scale magnetic cycle for a star other than the Sun. The magnetic field flips polarity every year. I will discuss the possible role of star-planet interactions on such a short cycle.
In addition to this observational aspect, I will discuss the effect the stellar magnetic field on the planet, planetary environment and planetary radio emission.
29.1.14 (Wednesday)
15:30
"New results on galaxy evolution from SpARCS, the Spitzer Adaptation of the Red-sequence Cluster Survey"
Chris LIDMAN (AAO, Australia)
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"New results on galaxy evolution from SpARCS, the Spitzer Adaptation of the Red-sequence Cluster Survey"

Chris LIDMAN (AAO, Australia)

Abstract

Covering the 50 square degrees of Spitzer SWIRE Legacy Fields, the Spitzer Adaptation of the Red-sequence Cluster Survey (SpARCS) is one of the largest surveys of its kind. It has detected hundreds of galaxy clusters up to z=1.7. Over the past few years, the SpARCS team has been examining the properties of galaxies in these clusters though multi-wavelength imaging and multi-object spectroscopy. In this talk, I will discuss what we are learning about galaxy evolution in these the densest of environments. I will also discuss our plans to push these studies to even higher redshifts where it seems that drastic changes to the galaxy population in the cores of clusters is occurring.