Due to the typical high atmospheric noise and low transparency, submillimeter observations can be carried out only from sites with very high atmospheric stability and very low precipitable water vapour content. The Antarctic Plateau is important because of its remarkable atmospheric transparency and stability. Logistical difficulties have limited till now the exploitation of the unprecendented potential of Antarctica as a site for submillimeter observations. The opening of Concordia Station at Dome C is now offering to the international astronomical community a unique opportunity to perform ground-breaking astronomical science. The proposal from our multi-national group represents a first step toward the realization of an international Antarctic Submillimeter Observatory (ASO) based on a telescope with a large collecting area (12 m diameter) to carry out both continuum and spectral line observations, particularly in the 200 and 225 μm atmospheric windows and possibly also in the Mid InfraRed at wavelengths ≳40 μm.

The Herschel Dwarf Galaxy Survey investigates the metal enrichment of the dust and gas in galaxies through observations of the local universe dwarf galaxies via the new far-infrared (FIR) and submillimetre imaging spectroscopic and photometric observations from the recently launched Herschel Space Observatory. The dust spectral energy distributions can now be constrained out to submm wavelengths and often show a submm excess in the low metallicity galaxies, which, if tracing very cold dust, could highlight large dust masses, sometimes not easily reconciled with their low-metallicity and observed gas mass. Additionally, Herschel observations of the FIR fine-structure lines probe the low density ionised gas, the HII regions and photodissociation regions. L[CII]/LCO is remarkably high in dwarf galaxies – typically an order of magnitude larger than more metal-rich starburst galaxies, pointing to a potentially significant reservoir of H2 not traced by CO but shielded in the C+-emitting envelopes. Thus a more accurate estimate of the molecular gas mass in low metallicity galaxies will be via the (CO + [CII]) to H2 conversion factor. The 88 μm [OIII] line is the brightest of all FIR lines in low-metallicity galaxies, sometimes 1.5 to 2 time brighter than the 158 μm [CII] line which is usually the dominate FIR coolant in normal spiral and starburst galaxies. The 88 μm [OIII] line may become the workhorse diagnostic for the high-redshift low-metallicity galaxies which will be targets for future submm observatories, such as ALMA. Further observations from The Herschel Dwarf Galaxy survey will provide a more complete picture of the nature of the dust and gas in low metallicity galaxies and thus a more comprehensive view of the chemical evolution of galaxies.

This paper presents some statistical information about the Concordia turbulent surface inversion layer, regarding height and turbulent energy, its contribution to the peculiar local seeing, and the free atmosphere seeing encountered just above this surface layer.

The era of high-precision astrometry has dawned upon us. The potential of Gaia μas-level precision in positional measuraments is about to be unleashed in the field of extrasolar planetary systems. The Gaia data hold the promise for much improved global characterization of planetary systems around stars of all types, ages, and chemical composition, particularly when synergistically combined with other indirect and direct planet detection and characterization programs.

We report the discovery of a new class of non-radial pulsating stars that are the precursors of low-mass white dwarf stars.

We describe recently proposed algorithms, denoted scaled gradient projection (SGP) methods, which provide efficient and accurate reconstructions of astronomical images. We restrict the presentation to the case of data affected by Poisson noise and of nonnegative solutions; both maximum likelihood and Bayesian approaches are considered. Numerical results are presented for discussing the practical behaviour of the SGP methods.

Red supergiants with their enormous brightness at J-band are ideal probes of cosmic chemical composition. It is therefore crucial to have realistic models of radiative transfer in their atmospheres, which will permit determination of abundances accurate to 0.15 dex, the precision attainable with future telescope facilities in galaxies as distant as tens of Mpc. Here, we study the effects of non-local thermodynamic equilibrium (NLTE) on the formation of iron, titanium, and silicon lines, which dominate J-band spectra of red supergiants. It is shown that the NLTE radiative transfer models enable accurate derivation of metallicity and effective temperature in the J-band. We also discuss consequences for RSG spectrum synthesis in different spectral windows, including the heavily TiO-blanketed optical region, and atmospheric structure. We then touch upon challenges of NLTE integration with new generation of 3D hydrodynamical RSG models and present the first calculations of NLTE spectra with the mean 3D model of Betelgeuse.

The SIM-Lite mission has finished its technology programme and continues with anengineering risk reduction activity while waiting for the results of the 2010 decadalreview. One of the last remaining activities is work on the SCDU testbed, which isdesigned to calibrate the spectral bias in interferometric astrometry to 0.1 microarcsec.This talk will provide a summary of engineering activities on building flight-likeprototypes of the key interferometer subassemblies, as well as an overview of the types ofproblems one encounters when attempting to do astrometry below 1 microarcsec, as well astheir solution.

Telescope pupils are usually not well suited for high dynamical range imaging. Central obstruction, telescope spiders, hard edges and sparseness (for interferometers) can make it very challenging to build a coronagraph. Fortunately, it is often possible to remap a telescope pupil to achieve high contrast imaging without loosing light. In the case of a monolithic telescope, pupil remapping can produce an apodized pupil with 2 aspheric mirrors which redistribute the light without introducing phase aberrations. Similarly, an interferometer pupil can be remapped into a tight configuration compatible with coronagraphic techniques.

Atomic diffusion – important in many contexts in stellar astrophysics and an important thread running through this meeting – is most spectacularly observable in the atmospheres of some A stars. The magnetic Ap stars and the non-magnetic Am stars show directly abundance anomalies caused by gravitational settling and radiative levitation. Over the last decade spectroscopic studies have begun to provide maps of abundance distributions in the magnetic Ap stars in three dimensions. Interestingly, high radial overtone p-mode pulsations in roAp stars have also given three-dimensional views of the stellar atmospheres with studies of rotational and line profile variations of pulsation amplitudes and phases. These detailed looks at the effects of microscopic atmospheric changes in the strongly non-LTE and magnetic upper atmospheric layers of Ap stars provide perhaps the most exciting challenge to atomic diffusion theory in terms of detailed explanation and prediction. Am stars were at one time thought not to pulsate because of gravitational settling of He from the He ii ionization zone that provides the κ-mechanism driving for δ Sct pulsations in A stars. In the last few years we have found with SuperWASP and Kepler observations that many Am stars do pulsate. More than half of all A stars pulsate at Kepler micromagnitude precision, yet there is a subset of A stars that truly do not pulsate at that level. Are these Am stars with the strongest signature of atomic diffusion? Is atomic diffusion the reason for the pulsational stability of these stars? The answers are not yet known.


We developed a 3D pure LTE radiative transfer code to derive observables expected for RSGs, with emphasis on small scale structures, from radiative-hydrodynamic (RHD) simulations of red supergiant stars (RSGs) carried out with CO5BOLD (Freytag et al. 2002). We show that the convection-related surface structures are observable with today's interferometers. Moreover, the RHD simulations are a great improvement over parametric models for the interpretation of interferometric observations.


We summarize the results of the Cosmic Microwave Background (CMB) working group of the ARENA project. The focus has been on precision measurements of CMB polarization (looking for the echoes of cosmological inflation) and high angular resolution CMB measurements (looking for Sunyaev Zeldovich effect in distant clusters of Galaxies, to probe the evolution of the Universe, Dark Matter and Dark Energy). For both projects the Dome C site represents the best choice worldwide.

In this work, based on Integral Field Unit spectroscopy observations on the Gemini South telescope, we study the spatial distribution of the He II λ4686 emission line and its relationship with the properties of the interstellar medium in two compact H II galaxies (Tol 0104-388 and Tol 2146-391). We explore the possible mechanisms responsible for this high-ionization emission line. Our preliminary results indicate that this emission line and its spatial distribution is associated with a mix of sources, where most of the emission is likely due to the ionizing radiation from radiative shocks originates by the presence of a myriad of unresolved star clusters in the central regions. Wolf-Rayet stars can be excluded as the primary source producing the observed morphology of the He II λ4686 emission line.

A major goal of contemporary astrophysics is understanding theorigin of the most massive galaxies in the universe, particularly nearbyellipticals and spirals. Theoretical models ofgalaxy formation have existed for many decades, although observationalevidence at both low and high redshifts is only beginning to put constraints on different ideas. We briefly describe theseobservations and how they are revealing the methods by which galaxies form by contrastingand comparing fiducial rapid collapse and hierarchical formation modelpredictions. The available data show that cluster ellipticals must haverapidly formed at z > 2, and that up to50% of all massive galaxies at z ~ 2.5 are involved in major mergers.While the former is consistent with the monolithic collapse picture, weargue that hierarchical formation is the only model that can reproduce all the available observations.

Atomic diffusion can have detectable effects in many kinds of stars, each time that mixing processes are not efficient enough to prevent the build up of abundance stratifications. In this talk, after presentation of some general aspects about diffusion processes in stars, I will discuss the role of radiative acceleration which is one of the important quantities determining diffusion velocities. I will also discuss some aspects specific to stellar atmospheres, in particular for stars exhibiting strong magnetic fields.

The NIR Ca II triplet has proven to be an important tool for quantitative spectroscopy. Here we present results of synthetic spectral analysis for the Ca II triplet for low-metallicity red giant stars, combined with observational data. Our results start to deviate strongly from the widely-used and linear empirical calibrations below [Fe/H] = −2. We provide a new calibration for Ca II triplet studies which is valid down until [Fe/H] = −4 and apply this new calibration to current data sets. We suggest that the classical dwarf galaxies are not so devoid of extremely low-metallicity stars as was previously thought and discuss preliminary results and possibilities for follow-up observations of these extremely low-metallicity candidates.

The analysis of hydrogen and metal absorption lines in the spectra of distant quasars (QSOs) has become a powerful method to study the distribution and physical properties of low-density gas situated in the extended halos and circumgalactic environment of galaxies at low and high redshift. We here review the overall properties of halo absorption-line systems seen in QSO spectra and discuss their connection to the Milky Way’s population of intermediate- and high-velocity clouds.

We present 3D high resolution numerical simulations of turbulent converging interstellar atomic hydrogen flows. First, we report pure hydrodynamical simulations from which we infer statistics of the CNM structures. We find that the CNM structures are characterized by a mass spectrum dN/dM ∝ M-1.7-1.8, a mass-size relation M ∝ L2.3-2.5, and a velocity dispersion σ ∝ L0.4-05. These are reminiscent of what has been inferred for CO molecular clumps. Then we present a 3D calculation, which includes magnetic field and self-gravity with the purpose of studying the formation of molecular clouds.

Testing instrument capabilities is a crucial issue for Gaia, where high levelperformances are expected. This activity involves many aspects: simulation of theinstrument through suitable modelling, comparison of the models with the actualinstrument, as well as producing evaluation methods, which are strictly related to the waydata will be processed and calibrated. In this paper I discuss the interconnections amongthese aspects, and provide some example from the current testing activities.

Over the last few years, evidence that nearby spiral galaxies are surrounded by massive halos of cold gas has been accumulating. This extra-planar cold gas, rotating more slowly than the disk gas, is observed in galaxies with a range of different properties (such as mass and star formation rate, SFR) and it appears analogous to the Intermediate and High Velocity Clouds of the Milky Way. Models for the origin of extra-planar gas have been proposed taking into account the effects of supernova feedback (galactic fountain), cooling flow accretion and hydrostatic equilibrium. Several techniques have been used from analytical treatments and ballistic orbit integration to hydrodynamical simulations. I present a new model where a galactic fountain sweeps up ambient medium as it travels through the halo. This seems to give the best results in reproducing the kinematics of the extra-planar gas and it implies a gas accretion rate of the order of the SFR of the host galaxy.