The observational constraints on interstellar dust are summarized. A dust model, consisting of a mixture of amorphous silicate, graphite, and PAH material that reproduces the observed interstellar extinction, is described. It is used to calculate the infrared emission expected when such dust is heated by radiation with the spectrum of interstellar starlight with various intensities. By adopting a suitable size distribution for the smallest carbonaceous grains (PAHs), and a distribution of starlight intensities, one can reproduce the observed global emission spectrum of galaxies. This allows the total dust mass, and the PAH abundance, to be estimated for any galaxy with a spectral energy distribution measured by the IRAC and MIPS cameras on Spitzer Space Telescope. For the Spitzer Infrared Nearby Galaxies Survey (SINGS) sample, galaxies with metallicities Z > 0.3 Z๏ tend to have a major fraction of their refractory elements in dust grains, just as in the Milky Way. For lower metallicity galaxies with extended H I envelopes, the overall dust-to-metals ratio remains uncertain. The PAH abundance index qPAH (the fraction of the total dust mass in PAH particles with NC < 103 C atoms) is dependent on metallicity: galaxies with Z <0.3 Z๏ have median qPAH = 1.1%, whereas galaxies with Z > 0.3 Z๏ have median qPAH = 3.5%. The reasons for the pronounced dependence of qPAH on metallicity remain unclear.

In this communication we study the statistics of Adaptive Optics remnant speckles, and we discuss how a coronagraph can defeat the noise associated with these speckles. At high Strehl Ratio regimes, residual speckles are pinned on the diffraction rings of the airy pattern. It can be shown that these speckles are due to small defaults of the wavefront, amplified by the coherent part of the wave and that the statistics of their intensity can be described by a modified Rice distribution. At low flux levels, a Poisson-Mandel transformation provides an analytical expression of the Probablility Density Function. We show the results of a numerical simulation and compare the results to the theoretical model. Simple analytical expressions can be derived for the variance of the noise.We discuss the efficiency of a coronagraph in terms of Signal to Noise Ratio, based on the analysis of the noise contributions which can be reduced by a coronagraph.

Exo-planets much fainter than their parent star are likely imageable atvisible wavelengths with a 2 to 8 meter space telescope equipped forcoronagraphy. The dynamic range can be further increased by nulling thespeckled star residue, before detection, with an adaptive hologram. Like theMach-Zehnder interferometer of Codona & Angel (2004), the hologramsubtracts from the stellar residue. a copy of it, made with the light rejectedby the Lyot mask. The final residue can in principle be as low as one photonper speckle, on average. It makes exo-Earths detectable if their Airy peakcontains a few photons. The method can also relax the difficult figuringtolerances for the pre-focal optics. With Lippmann-Bragg holograms, it canbe achromatized.

Comets are made of ices, organics and minerals that record the chemistry of the outer regions of the primitive solar nebula where they agglomerated 4.6 Gyr ago. Compositional analyses of comets can provide important clues on the chemical and physical processes that occurred in the early phases of Solar System formation, and possibly in the natal molecular cloud that predated the formation of the solar nebula. This paper presents a short review of our present knowledge of the composition of comets, focussing on volatiles. Implications for the origin of cometary materials are discussed.

Red Supergiant (RSG) represent a key-phase in the evolution of massive stars. These stars are characterized by strong mass loss of unknown origin. Observations show strong line profile fluctuations in depth, width and velocity, suggesting giant convective cells which could explain mass loss.Recently, radiative hydrodynamics (RHD) simulations of these stars show a peculiar convection pattern with giant cells. We performed 3D pure LTE radiative transfer calculations in snapshots of 3D hydrodynamical simulations taking into account the Doppler shifts caused by the convective motions. Computed spectra from RHD models qualitatively reproduce observations.


The oscillator strength is a key parameter in the description of the line absorption coefficient. It can be determined through experiment, abinitio and semi-empirical calculations, and backward analysis of line profiles. Each method has its advantages, and the uncertainty attached to its determination can range from low to indeterminable. For analysis of line profiles or equivalent widths the uncertainty in the oscillator strength can rival or surpass the difference between the derived element abundance from classical LTE and non-LTE analyses. It is therefore important to understand the nature of oscillator strength uncertainties and to assess whether this uncertainty can be a factor in choosing to initiate a non-LTE analysis or in the interpretation of its results. Methods for the determination of the oscillator strength are presented, prioritizing experiments, along with commentary about the sources and impact of the uncertainties. The Se I spectrum is used to illustrate how gf-values can be constructed from published data on atomic lifetimes and line intensities.

A new experimental setup is described that allows us to study the state-selected photodissociation dynamics of small molecules of astrophysical interest using two independently tunable VUV radiation sources.

Excellent seeing, coronal conditions, and very low IR thermal background are qualities of the Dome C/Concordia station site that will allow unique solar astrophysics science. We review the science case for inner corona observations (onset of the coronal heating mechanism still poorly understood) and the promises of high angular resolution to disentangle the possible mechanisms at work between waves, convection, and reconnection in this particularly magnetically structured solar atmosphere between the high chromosphere and inner corona. For coronagraphy, IR and high resolution possibilities, Dome C is a case by itself between classical ground-based sites and space opportunities. Telescopes from 50 cm (coronagraphy oriented) to 4 m (full high resolution advantage including IR access) are proposed to benefit from these remarkable observing capabilities. Using 3 × Ø50 cm off-axis telescopes, we first propose a medium size facility (1.4 m equivalent telescope) for very high resolution access, ADSIIC (Antarctica Demonstrator of Solar Interferometric Imaging & Coronagraphy), before the ultimate 9-telescope Solar Facility equivalent to a 4 m diameter telescope: A-FOURMI (Antarctica 4 m Interferometer). Finally, 30 m tower designs and their logistics using standard containers and elementary elements of 6 m maximum length, are presented and discussed. These towers are indeed of general interest also for the other optical and IR telescopes intended for Dome C/Concordia, allowing to get over most of the turbulent ground layer and to reach the best possible permanent seeing conditions (better than half an arcsec).

The open cluster Stephenson 2 contains the largest collection of red supergiants known in the Galaxy, and at present is the second most massive young cluster known in the Milky Way. We have obtained multi-epoch, intermediate-resolution spectra around the Ca ii triplet for more than 30 red supergiants in Stephenson 2 and its surroundings. We find a clear separation between a majority of RSGs having spectral types M0-M2 and the brightest members in the NIR, which have very late spectral types and show strong evidence for heavy mass loss. The distribution of spectral types is similar to that of RSGs in other clusters, such as NGC 7419, or associations, like Per OB1. The cluster data strongly support the idea that heavy mass loss and maser emission is preferentially associated with late-M spectral types, suggesting that they represent an evolutionary phase.

We present recent work undertaken by the Evolution and Seismic Tools Activity (ESTA) team of the CoRoT Seismology Working Group. The new ESTA-Task 3 aims at testing, comparing and optimising stellar evolution codes which include microscopic diffusion of the chemical elements resulting from pressure, temperature and concentration gradients. The results already obtained are globally satisfactory, but some differences between the different numerical tools appear that require further investigations.

The possibility to divide GRBs in different subclasses allow to understand better thephysics underlying their emission mechanisms and progenitors. The induced gravitationalcollapse scenario proposes a binary progenitor to explain the time-sequence in GRBs-SNe.We show the existence of a common behavior of the late decay of the X-ray afterglowemission of this subclass of GRBs, pointing to a common physical mechanism of their lateemission, consistent with the IGC picture.

Radio emission has been detected from all the stages of stellar evolutionacross the HR diagram. Its presence reveals both astrophysical phenomena andstellar activity which, otherwise, would not be detectable by other means. Thedevelopment of large, sensitive interferometers has allowed us to resolve theradio structure of several stellar systems, providing insights into the masstransfer process in close binary systems. I review the main characteristics ofthe radio emission from several kinds of stars, paying special attention tothose cases where such an emission originates in relativistic jets.

This course/paper deals with adaptive optics in the framework of astronomical imaging. It does not pretend to be an exhaustive course of astronomical adaptive optics. It is rather intended to give an introductory overview of it, from my very partial point-of-view.


The enrichment of the intergalactic medium with heavy elements is aprocess that lies at the nexus of poorly-understood aspects ofphysical cosmology. We review current understanding of the processesthat may remove metals from galaxies, the basic predictions of thesemodels, the key observational constraints on enrichment, and howintergalactic enrichment may be used to test cosmological simulations.


We present the science case for ICE-T, the International Concordia Explorer Telescope, a double telescope optimized for ultra-high and ultra wide field optical time-series photometry fromDome C. ICE-T consists of two 60 cm 8°×8°-FOV Schmidt telescopes for Sloan g and i photometry and one independent 25 cm, solar, full-disk, Ca ii-K imagingtelescope on a single mount. ICE-T is therefore operable during night and day. A 28 cm narrow-field Maksutov spectrophotometric telescope for night-time aerosol measurements (TAVERN-SP) will beprovided by AWI early on and operated in parallel with IRAIT and later with ICE-T. The low scintillation noise and the long continuous darkness are among the unique properties for highprecision optical time-series photometry.

Internal gravity waves are excited in stellar interiors thanks to turbulent convective regions, to opacity bumps and to tides when there is a close stellar or planetary companion. Then, they propagate in stably stratified stellar radiation zones where they deposit/extract angular momentum by damping processes and corotation resonances. This modifies the rotational evolution as well as the internal mixing in stars. In this review, we will present the state of the art for modelling such transport mechanisms with a peculiar focus on the most recent advances taking into account the influence of rotation, shear, and magnetic fields on internal gravity waves. Next, we will discuss consequences for stars dynamical evolution and what can be learnt from stellar seismology.

We use cosmological hydrodynamic simulations including galacticfeedback based on observations of local starbursts to find aself-consistent evolutionary model capable of fitting the observationsof the intergalactic metallicity history as traced by C iv betweenz = 6.0 → 1.5. Our main finding is that despite the relativeinvariance in the measurement of Ω(C iv) as well as the columndensity and linewidth distributions over this range, continualfeedback from star formation-driven winds are able to reproduce theobservations, while an early enrichment scenario where a majority ofthe metals are injected into the IGM at z > 6 is disfavored. Theconstancy of the C iv observations results from a rising IGMmetallicity content balanced by a declining C iv ionization fractiondue to a 1) decreasing physical densities, 2) increasing ionizationbackground strength, and 3) metals becoming more shock-heated at lowerredshift. Our models predict that ~20× more metals areinjected into the IGM between z = 6 → 2 than at z > 6. Weshow that the median C iv absorber at z = 2 traces metals injected 1 Gyr earlier indicating that the typical metals traced by C iv areneither from very early times nor from very recent feedback.

We report on new optical emission line observations toward the northern part of the Magellanic Stream. Using the Wisconsin H-Alpha Mapper (WHAM), we have detected Hα emission toward 17 directions spread across 50∘ of the Stream. We find strong variation in the Hα surface brightness with no significant correlation with Magellanic longitude. We compare our data with HI observations and briefly discuss the implications for the physical conditions of the Stream.

In the present review we summarize direct and indirect evidence that the massive close binary frequency is very large. Wethen discuss the binary evolutionary processes and we present a general massive close binary evolutionary scheme. Finally,we highlight the importance of massive close binaries for population number synthesis and the chemical evolution ofgalaxies.

IR spectroscopy is the premier tool to study the composition of interstellar dust. Broad absorption and emission bands provide direct identification of the solid compounds present in space and allow measurement of accurate abundances. Systematic studies of large samples of sources allow then inferences on the origin and evolution of dust in space. Overall, the observed infrared spectra of interstellar and circumstellar dust reveals an incredibly rich and varied composition. This chapter briefly reviews the principles of infrared spectroscopy. This is then applied to the composition of circumstellar oxides and minerals and interstellar Polycyclic Aromatic Hydrocarbon molecules.