In NLTE computations of trace elements in stellar atmospheres, background opacities are generally treated in LTE. It is thus important to assess the impact of different methods of including this background opacity on the statistical equilibrium of the trace element and its resulting NLTE abundance. This article illustrates these effects using two examples, nitrogen in Vega and carbon in the Sun.

Progress in our understanding of solar magnetism and activity rest to a large part on our ability to improve spatial resolutionfor resolving the solar surface magnetic fields fine structure. The solarcorona is permeated by magnetic fields emerging from the sun and, inturn, ejects particules and magnetic field into the heliosphere. It isof prime importance to measure the coronal magnetic field to understand mechanisms at work in the corona. We explain why Dome C isexpected to be an outstanding site for such observations and describethe Solar Brightness Monitor we prepare to probe sky background andaerosols levels at this site. We also discuss coronal observations Dome C could allow to obtain.

We provide a covariant derivation of plasma physics coupled to gravitation by utilizing the 3+1 formulation of general relativity, including a discussion of the Lorentz force law. We then reduce the system to the spherically symmetric case and show that all regions of the spacetime can be represented in a single coordinate system, thus revoking the need for junction conditions. We further show that the region exterior to the collapsing region is naturally described by the charged Vaidya spacetime in non-null coordinates.

Owing to its wide sky coverage and broad energy range, the FermiGamma-ray Burst Monitor (GBM) is an excellent observer of the transient hardX-ray sky. GBM detects about 240 triggered Gamma-Ray Bursts (GRBs) per year, includingover 30 which also trigger the Swift Burst Alert Telescope (BAT). Thenumber of GRBs seen in common with Swift is smaller than expected fromthe overlap in sky coverage because GBM is not as sensitive as the BAT and the GBM GRBpopulation is thus skewed to the brighter, closer bursts. This population includes about45 short GRBs per year, giving GBM an excellent opportunity to observe the electromagneticcounterpart to any gravitational wave candidate resulting from the merger of compactbinary members. The same characteristics make GBM an ideal partner for neutrino searchesfrom nearby GRBs, and for the elusive Very-High Energy (VHE) counterparts to GRBs. Withthe deployment of the next-generation gravitational-wave detectors (Advanced LIGO/VIRGO)and VHE experiments (CTA and HAWC) potentially within the lifetime of the FermiGamma-ray Space Telescope, the prospects for breakthrough observations aregood.

The proposed design for PILOT is a general-purpose, wide-field (1°) 2.4 m, f/10 Ritchey-Chrétien telescope, with fast tip-tilt guiding, for 0.5-25 µm. The design allows both wide-field and diffraction-limited use at these wavelengths. The expected overall image quality, including median seeing, is 0.28-0.3'' FWHM from 0.8-2.4 µm. Point source sensitivities are estimated.

In this paper we present some preliminary simulations concerning adaptive-optics-aided coronagraphy.The starting point used for this goal is the software system CAOS (Code for Adaptive Optics System),because of the simulation design ease given by its graphical programming environment, and thecompleteness and flexibility of its set of modules dedicated to adaptive optics (AO) simulations.We have so developed the complementary numerical tools necessary to implement the CoronographeInterférentielle Achromatique (CIA) within CAOS, together with differential imaging, andconsidering Fresnel propagation through the turbulent atmosphere. Hence we give an example ofapplication to exoplanet detection with the characteristics of the Very Large Telescope AO systemNAOS and the CIA.Finally, we also discuss on some other recent developments concerning CAOS.

In this lecture I present the way stars can be modeled in two dimensions and especially the fluid flows that are driven by rotation. I discuss some of the various ways of taking into account turbulence and conclude this contribution by a short presentation of some of the first results obtained with the ESTER code on the modeling of interferometrically observed fast rotating early-type stars.


In the past years a wealth of observationsallowed to unravel the structural properties of the Dark Matter Halos around spirals. First, their rotation curves followan Universal profile (URC) that can be described in terms of an exponential thin stellar disk and adark halo with aconstant density core, whose relative importance increases with galaxy luminosity. Careful studies of individual objects, from dwarfs to giants, reveal that dark halos have a core, whose size r0 correlates with the central density ρ0.These properties are in serious discrepancy with the cuspy density distribution predicted by N-body simulations in collisionless ΛCDM Cosmology.

Deconvolution is a necessary tool for the exploitation of adaptive opticscorrected images, because the correction is partial. The Maximum APosteriori (MAP) framework is used to derive a deconvolution method(MISTRAL) thatcombines the data with our knowledge of the noise statistics as well as ourprior information about the object and the variability of the Point SpreadFunction. The deconvolution of experimental and scientific data illustrates the capabilitiesof this method.

The advent of deep, wide, accurate, digital photometric surveys exemplified by the SloanDigital Sky Survey (SDSS) has had a profound impact on studies of the Milky Way. In thepast decade, we have transitioned from a scarcity to an (over)abundance of precise, wellcalibrated, observations of stars over a large fraction of the Galaxy. The avalanche ofdata will continue throughout this decade, culminating with Gaia and LSST. This newreality will necessitate changes in methodology, habits, and expectations both on the sideof the large survey projects as well as the astrophysics community at large. We argue,based on the experience with SDSS, that surveys should release data as early and often aspossible incorporating incremental improvements in each subsequent release, as opposed toholding off for a single, big, final release. The scientific community will need toreciprocate by performing analyses and (re-analyses) appropriate to the current fidelityof the released data, understanding that these are continually evolving and improvingproducts.

New observations of stellar pulsations, particularly from the CoRoT and Kepler space missions, have opened completely new possibilities for asteroseismic investigations for stars in large parts of the Hertzsprung-Russell diagram. Particularly dramatic has been the development of asteroseismology of stars showing solar-like oscillations, where hundreds of stars near the main sequence and tens of thousands of red giants can now be investigated. Although the analysis of the data have yielded extensive information about the global properties of the stars we are still only at the beginning of learning how to use the data for more profound studies of stellar interiors. Here I give a brief overview of the observations and discuss the potential contributions to the understanding of stellar physics.

We describe the current, 9-spacecraft Interplanetary Network (IPN). The IPN detects about325 gamma-ray bursts per year, of which about 100 are not localized by any other missions.We give some examples of how the data, which are public, can be utilized.

A report on the current status of the ESTA- Task 2 (oscillation frequencies comparison) is presented. Several types of comparisons have been made using the frequencies provided by different numerical codes. The equilibrium model is the same for all of them, and additionally some requirements such as boundary conditions, no re-meshing, etc, are also imposed. Some unexpected differences appear in the frequency and large separation comparisons. In the high frequency region these differences can be due to the order of the integration scheme used to solve the partial differential equations (or to the lack of number of mesh points in the outer layers). In the region around the fundamental radial mode and the low frequency region, important differences appear for the avoided crossing and the trapped modes respectively, the reason maybe due to the different sensitivity of each code to the profile of the Brunt-Väisälä frequency. The next step will be to test the accuracy of the codes using a model with a larger number of mesh points and with a better described Brunt-Väisälä frequency.

The Square Kilometre Array is a global project to develop the nextgeneration radio telescope at metre to centimetre wavelengths. It willhave a collecting area of order one million square metres, asensitivity 100 times higher than the extended VLA, an instantaneousfield of view (FOV) larger than the full moon, and, in some designs,more than one FOV allowing multiple simultaneous use. It will be anextremely powerful survey telescope with the capability to follow upindividual objects with high angular and time resolution. The SKA willreach a point source sensitivity of 25 nano-Jy in 1 hour ofintegration, and a maximum resolution of better than 1 milli-arcsecond at20 GHz with excellent imaging over several orders of magnitude at anygiven frequency. The SKA science reach will be enormous, allowing newdiscoveries in astroparticle physics and cosmology, fundamentalphysics, galactic and extragalactic astronomy, and solar systemscience. Technological innovation, closely paralleling commercial ITdevelopments, is key to the design concepts under investigation and tothe cost goal of USD 1000/m2. The selection of technologies for theSKA is scheduled in early 2008. A number of possible locations for thetelescope are under investigation with a choice scheduled in early2006. Construction of the array will take most of the next decade.


We consider the hierarchical three-body problem, with a binary and a planet-mass object. We investigate the effect of general relativity (GR) corrections to the Newtonian interactions. We focus on the Lidov-Kozai resonance, and the secular dynamics are analyzed over wide ranges of the semi-major axes and masses. We found regions in the parameter space where the GR corrections may be important for the long-term dynamics. We try to constrain the inclinations of putative Jovian planets in the recently announced binary systems of HD 4113 and HD 156846.

Regarding its seeing properties or its photometric quality aswell, the Dome C Concordia site is presented as being anintermediate solution between space and a good mountainobservatory. This statement still needs somewhat further nighttime confirmation. If really true, as is more and more expectedafter the preliminary site testing campaigns (Aristidi etal. 2004; Storey et al. 2004), thisopens extremely promising prospects for asteroseismology ofsolar-type stars, and also of any kind of star for which acontinuous observation much longer than 12 hours is an importantrequirement.

The main properties of pre-main-sequence (PMS) evolution are reviewed, withparticular emphasis on the impact of star formation studies. I will firstdiscuss the basic results established by the work of Hayashi, Iben andCameron in the early '60s. The changes introduced by the constraintsset by the previously ignored phase of protostellar evolution will bethen addressed. Evolutionary models including a variety of physical effects(accretion, rotation, magnetic field) are presented. Finally, theapplication of PMS models to reconstruct the star formation historiesof clusters and associations will be addressed.

A more complete view of a magnetosphere of a close orbit giant exoplanet, so called “Hot Jupiter”, based on the Paraboloid Magnetospheric Model (PMM), is proposed. The key element of the considered model consists in taking into account the effects of an expanding upper atmosphere of a Hot Jupiter heated and ionized by the stellar XUV radiation. As a result, an extended magnetodisk is built around the planet. The magnetic field produced by magnetodisk ring currents, dominates above the contribution of intrinsic magnetic dipole of a Hot Jupiter and finally determines the size and shape of the whole magnetosphere.

This paper reviews the various processes that have been proposed to explain the observedtrend of PAH strength with metallicity. It summarizes a study showing that, although PAHdestruction by hard radiation is important in low-metallicity environments, it is notsufficient to explain their paucity. In these systems, the deficiency of their formationmechanism, related to stellar evolution, has to be invoked.