Galactic globular cluster (GC) stars exhibit abundance patterns which are not shared by their field counterparts, namely the well-documented C-N, O-Na and Mg-Al anticorrelations. Recent observations provided compelling evidence that these abundance anomalies were already present in the intracluster gas from which the presently observed stars formed. A widely held hypothesis is that the gas was polluted early in the history of the GC by material processed through H-burning at high temperature and then lost by stars more massive than the observed long-lived stars. However the “polluters" have not been unambiguously identified yet. Most studies have focused on AGB stars, but rotating massive stars present an interesting alternative. Here we critically analyse the pros and cons of both potential stellar polluters. We discuss the constraints that the observational data bring on stellar nucleosynthesis and hydrodynamics as well as on nuclear reaction rates and we try to answer to the following question: “Are GC ideal laboratories to test stellar nucleosynthesis and hydrodynamics?"

The Gaia Attitude Model (GAM) is a simulation package that is developed to achieve adetailed understanding of the Gaia spacecraft attitude. It takes into account externalphysical effects and considers internal hardware components controlling the satellite. Themain goal of the Gaia mission is to obtain extremely accurate astrometry, and thisrequires a good knowledge of Gaia’s behaviour as a spinning rigid body under the influenceof various disturbances.

We present color-magnitude diagrams (CMD) reaching the oldest main sequence turn offs for three fields in the Fornax dwarf spheroidal galaxy, obtained with FORS1 at the VLT. One of them is situated at the center of the galaxy while the other two are located at a distance of 10′ form the center. We determine the full star formation history (SFH) of the central field, extending to the first star formation events.

We present new developments on the cosmic-ray driven, galactic dynamo, modeled by means of direct, resistive CR–MHD simulations, performed with ZEUS and PIERNIK codes. The dynamo action, leading to the amplification of large–scale galactic magnetic-fields on galactic rotation timescales, appears as a result of galactic differential rotation, buoyancy of the cosmic-ray component and resistive dissipation of small–scale turbulent magnetic-fields. Our new results include demonstration of the global–galactic dynamo action driven by cosmic-rays supplied in supernova remnants. An essential outcome of the new series of global galactic dynamo models is the equipartition of the gas turbulent energy with magnetic-field energy and cosmic-ray energy, in saturated states of the dynamo on large galactic scales.

A nonlinear radiative pulsating model for the long-periodic Cepheid l Carinae is presented. The LTE metallic lines and non-LTE hydroen lines are calculated and compared with the HARPS observations. We found that the weak and medium metallic lines well correspond to the radial Cepheid pulsation, while the Hα and some other strong lines reveal very strange behaviour which is not consistent with usual Cepheid pulsation. We conclude that l Car must have an extended circumstellar envelope, and discuss its possible parameters.

I describe aspects of the non-solar astronomyuse of Dome C telescopes under daytime/summerconditions. In the thermal IR (TIR) wavelengthregion, where scattered sunlight is dwarfed bysky and facility radiation, astronomy benefitsfrom the better seeing, continuous sky coverage,a more than doubling of the observing time andthe improved site accessibility and logistics.Na-Laser Guide Stars (LGSs) can be used forwavefront sensing in daytime using very narrowband filters to suppress the sky background atvisible wavelengths. It enables the use ofAdaptive Optics for diffraction limited imagingin the TIR during daytime at Dome C.

The atmospheric boundary layer contribution to the total seeing atDome C is presented in this paper. With a mean value of0.07'', this is one of the most stable boundary layerencountered. We discuss the temporal evolution of this part of theatmosphere and its relationship with meteorological parameters. Inwinter, the combined effects of the low wind speeds and low inversionlayer translate to the creation of little thermal turbulence above30 m.

This report provides the recommendations of ARENA Working Group 1 concerning the development of and objectives for a wide-field, optical/infrared, 2.5 m class telescope for Antarctica. It discusses the key science drivers for such a telescope, the performance and capabilities it should have, and the logistics and infrastructure issues relevant to its construction and operation.

Silicates form a major component of cosmic dust. This paper summarizes the main structural and spectroscopic properties of amorphous and crystalline silicates. Furthermore, it reviews our knowledge of cosmic silicates in the Galaxy. Recent in-situ studies of presolar silicates extracted from primitive meteorites and anhydrous interplanetary dust grains will be discussed.

We formulate the relation between the beam pattern and the source confusion limit.In the formula for the general number counts, the upper cutoff of the integration is set to obtain a numerically reasonable result.The upper cutoff corresponds to the beam area, so we input the beam pattern as the two-dimensional array of the Point Spread Function (PSF).Based on the representative number counts, we evaluate the source confusion typical of various infrared spacecrafts (e.g. ASTRO-F[1]).

We show that the XCO factor, which converts the CO luminosityinto the column density of molecular hydrogen has similar values for dense, fullymolecular gas and for diffuse, partially molecular gas. We discuss the reasons of thiscoincidence and the consequences for the understanding of the interstellar medium.

Interferometry in the visible now provides milliarcsecond spatial resolution and thus has been intensely used for studying the circumstellar environment of evolved and pre-sequence stars. Up to now, most of the scientific results were obtained using only the modulus of the visibility as a function of baseline, time or projected baseline (the so-called "super-synthesis" effect). In this paper we will try to show that even without images, the phase of the visibility is able to put very strong constraints on stellar modeling since it is possible to achieve μarsecond measurements using this technique. We will illustrate through two examples from the GI2T interferometer how the modulus and the phase of the visibility were used to understand the physics of Be disks. We will stress on the importance and the potential of coupling high angular resolution with high spectral resolution for the study of stellar physics. Finally, We will present a possible study on the phase signatures due to stellar rapid rotation that can be done using the VLTI interferometer.

Magnetic flux emergence as the mechanism leading to the formation of magnetized structures in the solar atmosphere plays a key role in the dynamic of the Sun. Observed as a whole, emerging flux regions show clear signs of twisted structure, bearing the magnetic free energy necessary to power active events. The high resolution observations of the recent solar observatories (e.g. Hinode, SDO) have revealed how intermittent the magnetic field appears and how various active events induced by flux emergence are. Magnetic field reconstructions methods show that the topology of the field in interspot regions presents a serpentine structure, i.e. field lines having successive U and Ω parts. Associated with the appearance of magnetic polarities, a tremendous number of brief small scale brightening are observed in different photospheric and chromospheric lines, e.g. Ellerman Bombs, along with small scale jet-like structures. These events are believed to be the observational signatures of the multiple magnetic reconnections which enable the magnetic field to emerge further up and magnetically structure the corona above active region. Meanwhile a world-wide effort to numerically model the emergence of magnetic field forming solar active region is been carried on. Using different types of physical paradigm – e.g. idealized magnetohydrodynamic model, advanced treatment of the physical equations, data-driven simulations – these numerical experiments highlight how electric currents can build-up during flux emergence, lead to reconnection and thus explain the formation of the different observed transients.

Our goal is to assess Gaia’s performance on the period recovery of short period(p < 2 hours) and small amplitude variability. To reach thisgoal first we collected the properties of variable stars that fit the requirementsdescribed above. Then we built a database of synthetic light-curves with short period andlow amplitude variability with time sampling that follows the Gaia nominal scanning lawand with noise level corresponding to the expected photometric precision of Gaia. Finallywe performed period search on the synthetic light-curves to obtain period recoverystatistics. This work extends our previous period recovery studies to short periodvariable stars which have non-stationary Fourier spectra.

The magnetic field of T Tauri stars is believed to be strong enough to disrupt the inner region of their accretion disk. At the inner disk edge, matter flows along the magnetic field lines at free fall velocity and accretes at the magnetic poles onto the star yielding hot accretion shocks on the stellar surface. I review the observational evidence supporting this magnetospheric accretion process in T Tauri stars and highlight recent results which point to a highly dynamic and time variable interaction between the inner disk and the stellar magnetosphere on timescales ranging from hours to months.

Although the theoretical study of very low metallicity (Z) and metal–free stars is not new,their importance has recently greatly increased since two related fields have been developing rapidly. The first iscosmological simulations of the formation of the first stars and of the reionisation period. The second is the observations of extremely metal poor stars. In this paper, we present pre–supernova evolution models of massive rotating stars at very low Z (Z = 10-8) and at Z = 0. Rotation has astrong impact on mass loss and nucleosynthesis. Models reaching break–upvelocities lose up to ten percents of their initial mass.In very low Z models, rotational and convective mixing enhancessignificantly the surface content in carbon, nitrogen and oxygen (CNO)when the star becomes a red supergiant. This induces a strong massloss for stars more massive than about 60 M๏. Our models predict typeIb,c supernovae and gamma–ray bursts at very low Z. Rotational mixingalso induces a large production of CNO elements, in particular ofprimary nitrogen. The stellar wind chemical composition is compatible with themost metal–poor star know to date, HE 1327–2326, for CNO elements. Ourmodels reproduce the early evolution of nitrogen in the Milky Way.

The growing awareness of the importance of the fossil record in the Milky Way forconstraining galaxy formation theory is reflected by the increasing number of new ground-and space-based surveys designed to unravel the formation history of the Galaxy. Recently,a new kinematic survey has been produced by means of spectro-photometric data from theSloan Digital Sky Survey (SDSS-DR7) and high-quality proper motions derived frommultiepoch positions from the Guide Star Catalogue II (GSC-II). In this framework, weassembled a sample of ~ 30 000 FGK nearby metal-poor (sub)dwarfs for whichselection and distance estimates take advantage of accurate stellar atmospheric parameters(effective temperature, surface gravity and metallicity) derived from SDSS spectra. Here,as one of the most interesting applications of this catalogue, we consider the feasibilityof probing fossil signatures of the formation of the Milky Way by selecting and analysingsubsamples of stars as tracers of the seven-dimensional space distribution (fullphase-space coordinates plus chemical abundance) of the Galactic halo population within afew kiloparsecs from the Sun. Preliminary results exhibit statistical evidence fordiscrete overdensities localised in kinematics and in the space of adiabatic invariants(angular momentum and energy). By examination of their intrinsic properties, we suggestthat they may be possible fossil signatures of past mergers or other accretion events.

We present an update on the performance of our 2 mm bolometer camera GISMO (the Goddard IRAM 2 Millimeter Observer), which is used for astronomical observations at the IRAM 30 m Telescope. The camera is optimized to efficiently observe dusty high-redshift galaxies. GISMO uses a monolithic 8 by 16 Backshort Under Grid (BUG) array with superconducting Transition Edge Sensors (TES). It serves as a testbed for our close-packed superconducting bolometer technologies and guides us in optimizing the design of future fast, low background bolometer cameras. Illustrated by astronomical observations we obtained recently, we demonstrate the scientific potential of the camera, highlighted by the detection of two high redshift galaxies.

Concordia has been the third permanent station inland the Antarctic continent since February 2005. It was built jointly by France and Italy in order to offer to the scientific community a platform for research on the antarctic plateau, high in altitude. After the very successful drilling programme EPICA at Dome C, an European project gathering 10 countries and offering the oldest accurate climate archive, many other field of science will benefit from the exceptional properties of the site, namely astronomical researches. This paper provides information on these properties and on the current facilities in terms of building and transport. In addition, it points out the environmental protection and waste management in force at Concordia, in agreement with the Antarctic Treaty and Madrid Protocol.

21-cm studies of the Galactic extra-planar gas layer can help us understand the origin of the gaseous Galactic halo and its interaction with the Milky Way disk. The 100-m Effelsberg radio telescope was utilized to detect and analyze a population of Hi halo clouds belonging to this layer, at Galactocentric radii R > 8.5kpc, following Galactic rotation. This sample of clouds has similar properties to the population detected by Lockman with the GBT at R < 8.5kpc. High resolution follow-up observations resolve them into a number of small, dense, cold arc-minute sized Hi cores. Their study provides evidence for a thermal equilibrium with the extended warmer envelopes. Single dish observations with the 300-m Arecibo telescope disclosed a sample of Hi clouds with similar properties. A power spectrum analysis of the Arecibo maps probes the characteristics of turbulence as a dominant physical process in the halo region.