"Resolving the BLR of the Quasar 3C273 with differential interferometry on AMBER"

Romain PETROV (Laboratoire LAGRANGE, OCA-UNS-CNRS)

Abstract

Unveiling the structure of the Broad-Line Region (BLR) of AGNs is critical to understand the quasar phenomenon. Resolving a few BLRs by optical interferometry will bring decisive information to confront, complement and calibrate the reverberation mapping (RM) technique, basis of the mass-luminosity relation in quasars. The RM diameters of BLRs are much smaller than the angular resolution of the VLT and Keck interferometers and they can be resolved only by very accurate measurements of differential visibility and phase as a function of wavelength. AGNs are well below the current magnitude limit for interferometry in high or medium spectral resolution, which is set by available fringe trackers. We have developed a "blind" observation method and a data processing based on the accumulation of 2D Fourier power and cross spectra. This permitted us to resolve for the first time a BLR, in the Paα line of 3C273 (K~10). After a careful analysis of the biases specific to observations at the limiting magnitude, we have obtained differential visibility and phase signals showing that the 3C273 BLR is much larger than the RM radius (more than 1200 light days for interferometry instead of 300 to 500 ld for RM). The gas producing the BLR actually extends beyond the inner rim of the dust torus. We also confirm that the BLR is very close to be pole-on, and show that the velocity field, and hence the emission line width, are dominated by local "turbulence" instead of global Keplerian rotation. We discuss a geometrical model of the 3C273 BLR that can explain the line profile, the RM and the interferometric measurements.

"Stellar Variability: Impact on the detection and characterization of exoplanets"

Isabelle BOISSE (U. Porto)

Abstract

Although extremely efficient, the radial-velocity (RV) technique to search and characterize planets is, however, an indirect method (as well as photometric transit detection or astrometry). One of the problems with this is the fact that periodic RV variations can in some cases be caused by some other mechanisms, not related to the presence of low-mass companions. Phenomena such as stellar pulsation, inhomogeneous convection, spots or magnetic cycles can prevent us from finding planets, they might degrade the parameters estimation, or give us false candidates, if they produce a stable periodic signal. We will consider the different kind of «noise » that are generated by stars, as well as the methods proposed and used to overcome this issue.

"Towards a more comprehensive understanding of exo-planetary worlds with direct imaging"

Laurent PUEYO (STScI)

Abstract

Direct imaging mitigates selection effects inherent to the currently known exo-planetary population since it is sensitive to objects in an orbital space orthogonal to the one available with indirect methods. Upcoming campaigns will survey young and adolescent stars and probe for signatures of their formation history using instruments designed for high-contrast imaging. In this presentation I will discuss the wealth of information accessible using such surveys and illustrate preliminary results from such campaigns. I will describe current methods and detail algorithmic progress pioneered by our team in order to identify and characterize with direct imaging the infrared radiation of young exo-planets orbiting nearby stars. I will illustrate how to take advantage of these techniques to analyze data from one of the largest homogenous direct imaging surveys to date: the aggregate of all HST-NICMOS coronagraphic observations carried out between 1998 and 2006. I will then present recent results obtained with the Project P1640 Integral Field Spectrograph, installed at the Palomar Hale Telescope, with a particular emphasis on the techniques we have developed for this class simultaneous multi-wavelengths observations and their impact on the characterization of the planetary systems already observed during the earlier stages of our 100 night survey.

"Measuring brightness asymmetries of red giants and supergiants with the VLTI/AMBER"

Pierre CRUZALEBES (Observatoire Cote d'Azur)

Abstract

High-angular-resolution observations of evolved stars reveal time-varying and large-scale deviations with respect to homogeneous photospheres. I will present the results of multiple observations, distributed over a two years period (2009-2011), made with VLTI/AMBER in the aim to reveal surface brightness asymmetries for 16 red giants and supergiants. Fine absolute calibration of raw instantaneous spectro-interferograms at the spectral channel level and fitting with chromatic atmospheric models allow to give reliable estimates of limb-darkened angular diameters. Fundamental stellar parameters are derived, linked to the departure from centro-symmetry. Correlations with Tc abundance and accuracy of astrometric parallax are searched.

"Preliminary results from bulge globular clusters proper motions"

Sergio ORTOLANI (U. Padova)

Abstract

Preliminary results of new, ground based CCD, proper motion measurements of galactic globular clusters projected in the direction of the bulge are presented. Most of them have more than 10 years of time base, and give reliable transverse motions in spite of their surprisingly small values. Combining the proper motions with the radial velocities and their positions (obtained from new distance measurements) we obtained the orbits using a model of gravitational potential optimized in the inner regions of the Galaxy. A new scenario of the properties of these clusters is derived, with at least two different families characterized by different kinematics. Implications on the size of the galaxy, the total number of inner bulge clusters and their formation are discussed.

"The Planet next door: An Earth-mass world orbiting Alpha Centauri B"

Xavier DUMUSQUE (U. Geneve)

Abstract

Nowadays, after having found hundreds of exoplanets, the radial-velocity (RV) technique starts to be limited by intrinsic stellar signals. Indeed, at the level of the best spectrographs, one starts to see the effects induced by stellar pressure waves, convection, surface activity coupled with stellar rotation, and magnetic cycles. The questions of how to extract and analyse the different types of stellar signals from RV data, and how to mitigate their contribution will be presented in detail. As result of this work, the smallest exoplanet detected with the RV technique have been announced. This planet, having a similar mass to Earth is also the closest one to the Solar System.

"A new spin on the Carina dwarf spheroidal galaxy"

Giuseppe BONO (Univ. of Rome Tor Vergata)

Abstract

Dwarf spheroidal (dSph) galaxies play a crucial role in many open astrophysical problems. We will outline some of them and we will focus our attention on stellar populations in the Carina dSph. In particular, we will discuss recent photometric and spectroscopic findings concerning the metallicity distribution and the identification of kinematic substructures. Finally, we will also discuss the pulsation properties of variable stars in nearby dwarf spheroidals and the role that they can play as stellar tracers.

"Science with the Virtual Observatory"

Amelia BAYO (ESO / MPIA, Heidelberg)

Abstract

The amount of public archival data available and multi-wavelength all sky survey missions are changing the way astronomical research is done. Although detailed studies on individual objects are of course necessary, the development of new tools and methodologies that ease the analysis of large amounts of multi-wavelength data in homogeneous and efficient ways is becoming mandatory. In this context, already in the early 2000 a world-wide philosophy was born: the "Virtual Observatory" that on the base of standardization of the data formats and data transfer protocols seeks to maximize the time for "real" science. In this talk I will give a brief introduction on how the Virtual Observatory was born and I will illustrate how useful it is with a number of published science papers based on this philosophy.

"The Herschel Planetary Survey: HerPlaNS"

Djazia LADJAL (University of Denver, USA)

Abstract

HerPlaNS is a Herschel Open Time program that exploits the unprecedented spatial resolving power in the far infrared (from 50um to 670um) of the Herschel Space Observatory to investigate a sample of 11 planetary nebulae (PNe). The aim of the program is to study the distribution of cold dust in the nebulae, using the PACS and SPIRE imaging modes, and to diagnose the physical conditions of the gas component using the PACS and SPIRE spectroscopy modes. The novelty of the study (apart from exploring a new wavelength range) is that our spectroscopy observations are spatially resolved which then allows us to compare the data to narrow band observations from Hubble and link the low energy regime of the PN to the high energy regime. PNe are unique objects that can be observed from the X-ray to the radio regime and the HerPlaNS data are essential in that they compliment the wealth of literature data we have at other wavelengths. This allows us to build a more complete picture of the PNe system in terms of evolution and energetics. In this presentation, I would like to introduce the HerPlaNS program, show its scientific potential and present some of our first results.

"Testing the Unification Model for AGN in the Infrared"

Cristina RAMOS ALMEIDA (IAC, Spain)

Abstract

I will present recent results on SED+spectroscopy fitting with CLUMPY torus models using subarcsecond resolution infrared data and a Bayesian approach. Our aim is to constrain and compare the properties of Type-1 and Type-2 Seyfert tori. We find that these dusty tori have physical sizes smaller than 10 pc radius, as derived from our fits. Unification schemes of AGN account for a variety of observational differences in terms of viewing geometry. However, we find evidence that strong unification may not hold, and that the immediate dusty surroundings of Type-1 and 2 Seyfert nuclei are intrinsically different in terms of covering factor. Finally, I will discuss the role of host galaxy obscuration in the fits.

"A precision distance to the Large Magellanic Cloud from eclipsing binaries and Cepheid variables"

Wolfgang GIEREN (Universidad de Concepción, Chile)

Abstract

I will report on the work of our group to improve the distance determination to the Large Magellanic Cloud to two percent, using eight unique eclipsing binary systems in the LMC. This new measurement represents a milestone for the calibration of the cosmic distance scale and improves the accuracy of the value of the Hubble constant. I will also report on the work of our group on Milky Way and LMC Cepheids which have yielded an independent precise distance to the LMC from the Infrared Surface Brightness Method, which serves as a check on the result from the eclipsing binaries

"Pushing AMBER to the limits"

Florentin MILLOUR (Observatoire de la Côte d'Azur)

Abstract

We have been conducting since 2011 a series of test campaigns to improve the AMBER observing strategy. The result is a jump of 2 magnitudes on the AMBER limiting magnitude. This improvement opens a wealth of new possibilities for AMBER, like increasing significantly the number of observable AGNs, accessing the AGNs Broad Line Region geometry, catching stellar types which were unreachable before, among other. I will briefly describe that observing strategy and show a few new results obtained with it.

"Eclipsing white dwarf binaries"

Steven PARSONS (Universidad de Valparaiso)

Abstract

In recent years multi-colour and transient surveys have lead to a large increase in the number of eclipsing white dwarf plus main-sequence star binaries. These binaries offer us a chance to test some of the fundamental concepts underpinning a wide range of astrophysical problems, ranging from exoplanet studies and supernova Ia, to compact binary evolution and the age of the Galaxy. I will present the results of our high-precision studies of these systems and show that they are ideal for testing both the white dwarf and low-mass star mass-radius relationships as well as models of binary evolution.

"The SINFONI view of the structure and internal workings of redshift 2 star-forming galaxies"

Alvio RENZINI (INAF, Padova Observatory)

Abstract

Major imaging and spectroscopic surveys of high redshift galaxies have delivered large samples of these objects that have allowed us to measure global quantities such as sizes, star formation rates and stellar masses, thus revealing some fundamental trends followed by galaxy populations. For a small, but representative number of them, it became possible to go further and study their internal structure and kinematics in greater detail. This has been accomplished with the Adaptive-Optics-fed SINFONI 3D spectrograph at the ESO VLT, that has delivered Halpha imaging and kinematics with ~1 kpc resolution for a few dozen galaxies at redshift ~2. These observations have revealed large rotating disk galaxies, along with other more compact and velocity dispersion dominated, whereas others appear to be mergers. Such large disks appear to host several actively star-forming clumps and are characterized by a much higher velocity dispersion compared to local galaxies. The presence of strong galactic winds, inferred from the profile of emission lines, adds further diversity of these galaxies compared to local spirals of similar stellar mass. Together with pioneering sub-mm observations, a detailed characterization of these galaxies is rapidly emerging which is providing us with fresh clues on galaxy formation and evolution.

"Multiplicity and fast accretion of ordinary chondrite parent bodies"

Pierre VERNAZZA (ESO, Garching)

Abstract

Planetesimal formation in the early Solar System is a very complex process through which initially submicron-sized dust grains evolve into rocky and/or icy planetesimals. The physical growth is accompanied by chemical, isotopic, dynamical, and thermal evolution of the protosolar disk material, processes important to understanding how the initial conditions determine the properties of the forming planetary systems (Apai and Lauretta 2009). Here we report evidence for establishing new constraints on the planetesimal formation process from newly available spectral measurements and mineralogical analysis of asteroids and unequilibrated meteorites that distinguish whether a chondrite was formed near the surface or in the interior of a planetesimal. This study illustrates, for the first time, i) that large groups of compositionally similar asteroids (clones) are a natural outcome of planetesimal formation, which direct implication is that meteorites within a given class can originate from several parent bodies ii) that the formation process of the H chondrite parent bodies must have been instantaneous which might be generalized to all planetesimals, and iii) the importance of radial mixing of disk material, the size-sorting of chondrules in particular, on the actual compositional heliocentric gradient among asteroids with LL parent bodies having formed – surprisingly - closer to the Sun than H ones.

"Ionization of the diffuse gas in galaxies"

Christophe MORISSET (IA-UNAM, Mexico)

Abstract

Hot low-mass evolved stars at work. We revisit the question of the ionization of the diffuse medium in late type galaxies, by studying NGC 891, the prototype of edge-on spiral galaxies. The most important challenge for the models considered so far was the observed increase of [O iii]Hβ, [O ii]Hβ and [N ii]Hβ with increasing distance to the galactic plane. We propose a scenario based on the expected population of massive OB stars and hot low-mass evolved stars (HOLMES) in this galaxy to explain this observational fact. In the framework of this scenario we construct a finely meshed grid of photoionization models. For each value of the galactic latitude z we look for the models which simultaneously fit the observed values of the [O iii]Hβ, [O ii]Hβ and [N ii]Hβ ratios. For each value of z we find a range of solutions which depends on the value of the oxygen abundance. The models which fit the observations indicate a systematic decrease of the electron density with increasing z. They become dominated by the HOLMES with increasing z only when restricting to solar oxygen abundance models, which argues that the metallicity above the galactic plane should be close to solar. They also indicate that N/O increases with increasing z.

"Atmospheric characterisation of exoplanets: towards terrestrial planets"

David EHRENREICH (U. de Geneve)

Abstract

Spectroscopy of exoplanetary transits is our most powerful tool to characterize the atmospheric structure and composition of exoplanets. For the last 10 years, this technique provided a wealth of new insights on the atmospheres of irradiated giant planets. It has been recently applied to smaller exoplanets, from hot Neptunes to super-Earths. The atmospheric characterisation of super-Earths is difficult because of their tenuous transit signals, their compact atmospheres, the presence of hazes or clouds, and their uncertain natures: are they rocky, ocean-planets, or sub-neptunes? Observing transits across bright, nearby stars, is the key to solve these difficulties and a major goal of the CHEOPS mission recently selected by ESA. In the light of the recent exciting discoveries of several super-Earths around bright stars, I will present our current attempts to characterize some of these planets from space with the Hubble Space Telescope, and discuss some prospects to tackle the huge challenge that is the atmospheric characterisation of Earth-like planets.

"The solution of the Fundamental Plane problem"

Mauro D'ONOFRIO (University of Padova, Italy)

Abstract

We show that the fine-tuning between stellar structure and population is the key to understand the FP tilt and tightness. In particular we demonstrate that the relations between the Sersic index n, the mass of the galaxies M* and the mass-to-light ratio M*/L (nMML relation), is just the fine-tuning the produces most of the observed tilt. On the other hand, stellar population variation cannot account of the bulk of the tilt, but only of the differential tilt observed at the various wavelengths.

"Multiple stellar-mass black holes in globular clusters"

Anna SIPPEL (ESO, Chile)

Abstract

While tens or hundreds of stellar-remnant black holes are expected to form in globular star clusters, it is still unclear how many of those will be retained upon formation, and how many will be ejected through subsequent dynamical interactions. No such black holes have been found in any Milky Way globular cluster until the recent discovery of stellar-mass black holes in M22. I present a direct N-body model of a star cluster similar to M22. Multiple stellar-remnant black holes are retained at a cluster age of 12 Gyr and I illustrate the dynamical history of the black hole population in this model. This will show that multiple black holes could be present in any Milky Way globular cluster with an extended core (as it is the case for M22 or the N-body model presented here).

"Galaxy Interactions in Compact Groups : The Galactic Winds of HCG16"

Frédéric VOGT (Mount Stromlo Observatory, Australia)

Abstract

In my PhD, I have undertaken a series of observations of star-forming galaxies in Compact Groups (CGs) with the WiFeS integral field spectrograph. This project investigates the physics of galaxy interactions, the formation of galactic winds, and the onset of star formation episodes in a CG environment. In this presentation, I will present the first outcome of this project: the analysis of the galactic wind of NGC838 in HCG16, an asymmetric, bipolar, rotating structure, powered by a nuclear starburst. I will then compare this wind with the neighbouring wind in NGC839, which gives us clues regarding galactic winds formation mechanisms and the group interaction history.

"A Possible Close-in Low-mass Stellar Companion to the Transitional Disk Star HD 142527"

Beth BILLER (Institute for Astronomy, Honolulu, HI)

Abstract

With the uniquely high contrast within 0.1" (Delta(mag)(L') = 5-6.5 mag) available using Sparse Aperture Masking with NACO at Very Large Telescope, we detected asymmetry in the flux from the Herbig Fe star HD 142527 with a barycenter emission situated at a projected separation of 88 ± 5 mas (12.8 ± 1.5 AU at 145 pc) and flux ratios in H, K, and L' of 0.016 ± 0.007, 0.012 ± 0.008, and 0.0086 ± 0.0011, respectively (3σ errors), relative to the primary star and disk. After extensive closure-phase modeling, we tentatively interpret this detection as a close-in, low-mass stellar companion with an estimated mass of ~0.1-0.4 M sun. Multi-band followup to confirm orbital motion and rule out disk emission is necessary and is scheduled for March 2013. HD 142527 has a complex disk structure, with an inner gap imaged in both the near and mid-IR as well as a spiral feature in the outer disk in the near-IR. This possible low-mass stellar companion may provide a critical explanation of the observed disk structure.

"AGN Large-scale clustering measurements: What can we learn?"

Mirko KRUMPE (ESO, Garching)

Abstract

In the last decade, large area surveys (e.g., SDSS, 2dF, XMM-COSMOS) significantly improved AGN clustering measurements, which now provide tight constraints on the mass of the hosting dark matter halos (as a function of AGN luminosity, type, and redshift), the environment in which super massive black hole accretion takes place, and the co-evolution of galaxies and AGNs. First, I will give a very basic introduction to AGN clustering measurements. I will explain how large-scale clustering is measured and which physical processes cause the observed AGN clustering signal. I will summarize current AGN clustering measurements, analysis techniques, and the current picture of AGN large-scale clustering. This includes the results of a series of recently published papers that measure and analyze the clustering of X-ray selected AGNs. By using the cross-correlation function (CCF) with the Sloan Digital Sky Survey (SDSS) galaxies, we achieve the most precise clustering measurements for broad-line AGNs at low redshifts (z<0.5). Finally, I will briefly discuss which groundbreaking new results future AGN clustering measurement will deliver in the research fields of cosmology and AGN/galaxy co-evolution.

"Cepheids from long-baseline interferometry"

Alexandre GALLENNE (Universidad de Concepcion, Chile)

Abstract

Cepheid stars are powerful astrophysical laboratories providing fundamental clues for studying the pulsation and evolution of intermediate-mass stars. Studying these stars in binary systems is particularly important for several reasons: 1) the scatter on the Cepheid P-L relation could be reduced if the effect of companions is well known, 2) it could lead to a better understanding of the age and evolution of Cepheids, and 3) it is necessary to estimate the dynamical masses of Cepheids and constrain theoretical models of their pulsation and evolution. However, most of the companions are located too close to the Cepheid (~1–15 mas) to be observed with a 10-meter class telescope. The only way to spatially resolve such systems is to use long-baseline interferometry. Last year we started a unique and long-term interferometric program that aims at detecting and characterizing physical parameters of the companion of some binary Cepheids, using the multi-telescope recombination instruments VLTI/PIONIER and CHARA/MIRC. In this talk, I will present the first and impressive results of our MIRC observations for the Cepheid V1334 Cyg

"The Salty Surfaces of Jupiter’s Trojan Asteroids and Implications for Astrobiology"

Bin YANG (IFA, Hawaii)

Abstract

With a total mass comparable to the main asteroid belt, the Trojan asteroids are a major feature in the solar system. Their composition hold the key to answering fundamental questions about planetary migration, the late heavy bombardment, and the origin and evolution of transneptunian objects (TNOs). I conducted a dedicated multi-wavelength survey on the Trojans to search for diagnostic features of water ice, organics and hydrated silicates. In addition, I constructed a modified Mie/Hapke hybrid model to understand the surface structure of these objects. My study shows that the Trojan spectra over a wide wavelength range can be consistently explained by ~1wt% silicates and 2-10 wt% highly absorbing material (such as carbon or iron) suspended in a transparent salt matrix. The origin of the salt matrix can be explained by the thermal evolution if Trojans are composed of primitive silicates and water ice upon formation. The heat from the decay of radionuclides melts the sub-surface ice, causing water to flow and mix with soluble materials to form brine below the cold crust. Impact erosion of the primitive crust then exposes the sub-surface brine, which eventually sublimates leaving behind a salt mantle. It is noteworthy that appropriate salts are better known within biology for stabilizing delicate molecular structures fundamental to life's chemistry. The general conditions of water ice, organics and hydrated silicates on Trojans are, in many ways, a close match to classic thinking about the prebiotic chemistry that gave rise to life.

"H3+ absorption line survey in the Central parsec of the Galaxy"

Miwa GOTO (Muenchen Observatory)

Abstract

The cosmic-ray ionization rate is an old and new question of astrophysics. It is the rate how often a hydrogen atom or molecule in the ISM is ionized by the hit of a cosmic ray. This obscure number is in fact one of the most powerful influencers that shows up every corners of astronomy. For instance, secondary electrons are the main heat source of the ISM via the collisions with the gas. Ionized gas tied to the magnetic field controls the dynamics of the gas, therefore the timescales of star formation. Ion-neutral reaction is the primary drive of the ISM chemistry, as neutral-neutral reaction is prohibitively slow in the cold temperature. We will present how one can get hold of the cosmic ray ionization rate in the ISM with the spectroscopy of the ion-molecule H3+, and discuss an unexpected connection of H3+ spectroscopy to the dark matter in the central one parsec of the Galaxy.

"Obscured AGN in the golden epoch of galaxy-AGN coevolution: perspectives for IR and mm observations"

Marcella BRUSA (MPE, Germany)

Abstract

Over the last few years, the existence of mutual feedback effects between accreting supermassive black holes powering AGN and star formation in their host galaxies has become evident. As a consequence, the search for, and the characterization of the evolutive and physical properties of (obscured) AGN over a large redshift interval is a key topic of present research in the field of observational cosmology. Significant advances have been obtained in the last ten years thanks to the sizable number of XMM-Newton and Chandra surveys, complemented by multi-wavelength follow-up programs. After a brief review on how and why X-ray surveys are critical in studying and characterizing AGN, I will focus on the most recent results on AGN-galaxy co-evolution and in particular on observed AGN and galaxy properties. I will also present the science cases for observations at longer wavelengths and show how these new observations may be useful to discriminate among different models of AGN triggering towards a better understanding of the co-eval AGN-galaxy growth.

"WD0837+185 - A substellar cuckoo?"

Sara CASEWELL (Leicester University, UK)

Abstract

There is a striking and unexplained dearth of brown dwarf companions in close orbits (< 3AU) around stars more massive than the Sun, in stark contrast to the frequency of stellar and planetary companions. Although rare and relatively short-lived, these systems leave detectable evolutionary end points in the form of white dwarf - brown dwarf binaries and these remnants can offer unique insights into the births and deaths of their parent systems. I will present the discovery of a close (orbital separation ~0.006 AU) substellar companion to a massive white dwarf member of the Praesepe star cluster. I will discuss the evolution of this system and examine the various formation scenarios, concluding that the substellar object was most likely to have been captured by the white dwarf progenitor early in the life of the cluster, rather than forming in situ.

"Seismology of Pre-Main-Sequence Stars: This should be easy. Why isn’t it?"

David GUENTHER (Saint Mary’s University, Canada)

Abstract

Pre-main-sequence stars are chemically simple stars, not yet nuclear burning, that are seismically active when they pass through the delta Scuti instability strip. As such these homogeneous spheres of mainly hydrogen and helium should exhibit an oscillation spectrum that is simple to model. This is not the case. PMS stars present a wide variety of oscillation characteristics that, except for one specific type, have defied straight forward modelling. Allow me to explain.

"The evolution of protoplanetary disks in T Tauri binary systems"

Sebastian DAEMGEN (Toronto University, Canada)

Abstract

Binaries are the most common outcome of star formation. The impact of a stellar binary companion on the evolution of a circumstellar disk, however, is complex and largely unknown. Consequently, star and planet formation in binaries may be significantly different than in single stars. In the largest coherent study of the evolution of circumstellar disks around the components of binary stars to date, we observed 52 binaries in the Orion Nebula Cluster and Chamaeleon I star-forming regions with near-infrared photometry and spectroscopy. In this talk I will summarize the findings, e.g. a significant acceleration of disk evolution in the closest binaries with separations <100AU, and give a short outlook of future projects in the field.

"Constraining the Magnetic Field Strength in Soft X-ray Intermediate Polars"

Seppo KATAJAINEN (Tuorla Observatory, Finland)

Abstract

The evolutionary connection between two subclasses of magnetic of Cataclysmic Variables (CVs), polars and intermediate polars (IPs) is not yet well established. In the former, the spin period of the accreting white dwarf is synchronised with the binary orbital period while in the latter it is not. Soft X-ray IPs are good candidates for progenitors of polars, but their magnetic field strengths are poorly constrained. A big fraction of them are known to be circularly polarized but converting polarized fractions into magnetic field strengths is problematic, so it is still unclear whether they are of comparable magnetic field strength to polars or not. Only a comprehensive polarimetric study of a sample of soft X-ray IPs is able to reveal their magnetic field strengths, by detection of cyclotron emission humps in their optical/IR spectra. Our studies have provided some evidences that some IPs have comparable magnetic field strengths to some polars and can hence evolve from one to the other.

"Planets from the Calan-Hertfordshire Extrasolar Planet Search"

James JENKINS (Universidad de Chile)

Abstract

I will introduce some of the recent work being done as part of the Calan-Hertfordshire Extrasolar Planet Search (CHEPS). I will discuss our radial velocity work and methods to extract Keplerian orbits from undersampled data and from low S/N data and then discuss some new planetary systems we have recently discovered.

"Can we trust CO as a probe of densities and temperatures in molecular clouds?"
Faviola MOLINA (University of Heidelberg, Center of Astronomy, Institute for Theoretical Astrophysics)

Abstract

I will present the analysis of one numerical simulation as a good example of a typical Galactic molecular cloud in order to help us understand how to interpret temperature and density inferred from the CO line emission map. We find that the kinetic temperature is always underestimated if it is inferred only from the excitation temperature, Tex, from 12CO(1-0) emission line. On the density analysis, we find that CO primarily traces material at high densities. Besides, by considering a fix value of the CO-H2 conversion factor, the 12CO(1-0) emission map underestimates the density (therefore the mass of H2) at low column densities. In this scenario, the total H2 mass of the cloud, inferred from the emission map, is only 60% of the actual mass of the cloud.

"Near Infra-Red spectra of small icy bodies in the Solar System"

Florian GOURGEOT (ESO, Chile)

Abstract

The study of the icy-bodies of the outer solar system provides data of paramount importance to understand the mechanisms of planetary accretion and the role of water in planetary evolution. Water itself is the primary ”volatile” encountered in its solid state beyond Jupiter’s snow line. As my "ESO PhD student time" is now almost over, I will present the work I did during these two years : First, I will show new H &K bands spectra of the Uranus’ icy satellite Miranda. This body is probably the most remarkable of all satellites of Uranus, displaying a series of surface features such as faults, craters and large-scale upwelling, remnant of a geologically very active past. The observations were performed first at the Palomar Observatory with the PHARO instrument (Palomar High Angular Resolution Observer) and then at the Mauna Kea Observatory with SpeX instrument based on the IRTF (Infra-Red Telescope Facility). Then, I will also present new observation results of Haumea, one of the biggest TNO (Trans-Neptunian Object). With it being approximately 2000 x 1600 x 1000 km in size, Haumea's extreme elongation makes it unique among known dwarf planets which is linked to a rotational deformation due to its extremely short 3.9-hour rotation period. Although a high bulk density estimated at a range of 2.6 to 3.3 g.cm-3 suggests a more rocky composition than other KBOs, Haumea and its satellites are considered by a crystalline water-ice multiple system (Dumas et al. 2011). Moreover, Haumea has become the second Kuiper Belt Object after Pluto to show observable signs of surface features. Indeed, a region darker and redder than average on the surface of Haumea has been identified (Lacerda, 2010). Our recent results combining data from several epochs from the Very Large Telescope obtained in Near Infra-Red [1.6 to 2.4 μm] with the integral-field spectrograph SINFONI permit us to provides some characteristics about this dark red spot. Finally, I will briefly show some actual results and perspectives on other icy targets like Jovian moons, and interesting results I obtained on laboratory experiments in Grenoble (France) on icy components (such as methanol) to constrain reflectance models used in the study of several icy bodies.

"Cosmology: CMB and Dark Energy"

Sidney BLUDMAN (University of Pennsylvania, USA / Universidad de Chile)

Abstract

We will review the history of our universe, the latest CMB observations, and probes of the Dark Energy. The evolution of the Universe and the growth of structure is well fitted by six-parameter of the Concordance Model (LCDM).

"Cosmological Dark Energy Observations and Theoretical Interpretations"

Sidney BLUDMAN (University of Pennsylvania, USA / Universidad de Chile)

Abstract

Because our Universe is apparently homogeneous, isotropic and spatially flat, it is described in general relativity by an expanding flat Robertson-Walker metric. We will describe how its expansion history has been observed by cosmic luminosity or angular aperture distances measured for the matter-radiation epoch in the CBR, for the acoustic horizon in the baryon oscillations, and for supernova Ia at red-shift z < 2. Parametrization of this expansion history leads to the Concordance Model ACDM for the recently accelerating cosmic expansion, which hopefully will emerge from four-dimensional general relativity models for dark energy or from higher-dimensional models extending general relativity. In any case, revolutionary phenomenological and epistemological conclusions emerge from the recent discovery of the accelerating cosmic expansion.

"The Milky Way bulge as probed by microlensed dwarf stars"

Thomas BENSBY (Lund University)

Abstract

I will present the most recent results from our ongoing VLT/ToO program aimed at observing dwarf stars to trace the chemical evolution of the bulge. The age distribution, metallicity distribution, and the elemental abundance trends show that the bulge is a very complex region in the Galaxy.

"Magnetic Fields in Bok Globules"

Gesa BERTRANG (Universitaet zu Kiel, Germany)

Abstract

The influence of magnetic fields on the star-forming process is still an open question, although a very important one. The best environment to study this influence is given in low-mass star-forming regions, called Bok globules. These objects are less effected by other effects like large-scale turbulences. The magnetic field strength and structure in the dense inner of the globules can be determined by observing the polarized reemission of aligned dust grains in the sub-mm. The magnetic field in the outer, less dense parts of the globules can be traced by observing polarized radiation of background stars in the optical or near-IR. Thus, multi-wavelength observations reveal the magnetic field strength and structure across the entire globule. To study the magnetic field in low-mass star formation I make use of both, numerical simulations and observations of aligned dust grains. The numerical simulations are based on a 3D radiative transfer code where the 3D density distribution, dust properties and the 3D magnetic field structure are free parameters and can therefore be fitted to or constrained by observations. The polarimetric observations are carried out in the sub-mm, near-IR and the optical to trace the globules magnetic field on large scales. Combined with the modeling they provide new insights into the role of magnetic fields in the star-forming process.

"Spectropolarimetric Studies of Type Ia SNe "

Alejandro CLOCCHIATTI (P. Universidad Catolica de Chile)

Abstract

During the last few years, our group has collected spectropolarimetric observations of 17 Type Ia SNe, including both normal and peculiar events. In depth study of the database is starting to reveal facts that need to be incorporated into the paradigms we have at hand to understand SNe Ia progenitors and explosions, or creatively interpreted to modify them. I will show preliminary results from the work of my Ph. D. student at Pontificia Universidad Catolica, Paula Zelaya. They include Type Ia SN that display continuum polarization which, almost certainly, is not of interstellar origin, others which, according to probable scenarios of progenitor evolution should not be spherically symmetric, but seem to be, and late time data that contradict our nascent wisdom on how Type Ia polarization signals should evolve with time.