We present a new multi–fluid, grid MHD code PIERNIK, which is based on the Relaxing TVD scheme (Jin & Xin 1995). The original scheme (see Trac & Pen 2003; Pen 2003) has been extended by an addition of dynamically independent, but interacting fluids: dust and a diffusive cosmic ray gas, described within the fluid approximation, with an option to add other fluids in an easy way. The code has been equipped with shearing–box boundary conditions, and a selfgravity module, Ohmic resistivity module, as well as other facilities which are useful in astrophysical fluid–dynamical simulations. The code is parallelized by means of the MPI library. In this paper we present an extension of PIERNIK, which is designed for simulations of diffusive propagation of the Cosmic–Ray (CR) component in the magnetized ISM.

Hereafter we give a brief history of our contribution to astronomical site testing in Antarctica, at least for thehigh angular resolution in the visible range. The decision to undertake the first site testing at South Pole began one year after a congress organized by French Académie des Sciences, in year 1992. Indeed, in 1993 a meeting took place in Chicagowith the participation of Peter Gillingham, Al Harper and Jean Vernin where each one took the respectiveresponsibility of 1) giving a PhD student, 2) the South Pole infrastructure and 3) the relevant instruments.During winter 1995, thanks to a mast equipped with micro-thermal sensors, we demonstrated (Marks et al., 1996, A&AS, 118, 1)that the first 30 m of the surface layer was disrupted by strong optical turbulence. Then, the year after,15 balloons equipped with micro-thermal probes were successfully launched from South Pole. Marks et al. (1999, A&AS, 134, 161)shown that most of the optical turbulence at South Pole was concentrated within a layer 200 m thick abovethe ice level.From this study, it becomes clear that the noticeable katabatic wind present at South Pole was generatingthis huge surface layer and that is why we oriented our astronomical site characterization towardDôme C.
Our first summer seeing estimations began in 2000, which demonstrated (Aristidi et al., 2003, A&AS, 406, L19 & Aristidi et al., 2005, A&A, 444, 651)that, as expected, the surface wind was much less than at South Pole, and, as a matter of fact, the seeingwas much better, and was even exceptional during the four hours of the afternoon where a seeing of less than 0.5 arcsec was measured. In 2005, the Concordia base was first open during the polar night, and one of us,A. Agabi was able to launch 41 balloons equipped with micro-thermal sensors. A differential image motionmonitor (DIMM) was also setup with success. At mid winter, Agabi et al. (2006, PASP, 118, 344) showed that mostof the optical turbulence came from the first 30 m surface layer and very little from the rest of theatmosphere (1.3 arcsec above 8.5 m and 0.37 arcsec above 30 m).

This paper reports the first results obtained on thephotodissociation of the isolated PAH cations 12C24H+12,13C12C23H+12 and 12C24H+10, usingthe astrochemistry experimental set-up PIRENEA.The dissociation patterns of these ions involvethe loss of pairs of hydrogen atoms. A first interpretation indicates that the-H2 dissociation path is favoured compared to the -H path in ourexperimental conditions. These results might have important implicationson the formation of H2 in the interstellar medium.

We discuss our ideas how to make best use of the Antarctica Dome Csite equipped with a 2.4 m infrared telescope (“Hubble on the ground”),including day time observations of the Magellanic Clouds in the 3 monthsAntarctic Summer.

This paper describes a coronagraphic nulling interferometer calledKEOPS (Kiloparsec Explorer for Optical Planet Search) to be placedon the Dome C plateau of Antarctica. KEOPS is an interferometricarray of 39 1 m–2 m telescopes spread over kilometric baselines andoperated in the thermal IR region. It could search and characterizeall potential exoEarths within the 1 kpc diameter region observablefrom Dome C. We argue that even in the very difficult operationconditions of Antarctica, such a facility can compete at a muchlower cost with the non-zero risk space missions, both for for ExPNssearch and their spectroscopic characterization plus sub-massnap-shot imaging of galactic and extra-galactic compact sources.

More than 100 reactions between stable molecules and free radicals have been shown to remain rapid at low temperatures. In contrast, reactions between two unstable radicals have received much less attention due to the added complexity of producing and measuring excess radical concentrations. We performed kinetic experiments on the barrierless N + OH and N + CN reactions in a supersonic flow (Laval nozzle) reactor. The results provide insight into the gas-phase formation mechanisms of molecular nitrogen in interstellar clouds (ISCs).

Debris disks are dusty and/or gasous disk that are viewed in scattered light and thermal emission around stars around 107–108 yr. It is well known that the dust in these system is not primodial. It is short lived and must be continuously replenished by colliding planetesimals. Most of them appear distorted by the gravitational pertubations by inner planets or stellar companions. This is why these systems are viewed today as young planetary systems. 
Debris disks are collisional systems. Thanks to collisional cascade towards smaller size, the dust particles are transported outwards by radiation or stellar wind pressure. Below a given blow-off size they escape the system. This model explains the radial density profiles observed.
The various asymmetries, clumps and other dynamical structures such as spiral arms are though to originate in gravitational perturbations by planets and/or companions. Planets usually create gaps in disks, but they also sculpt disks via their mean-motion resonances. Clumpy structures are often invoked as resulting from such an interaction. Stellar companions usually truncate the disk, sometimes confining them to thin annular structures. They also help creating spiral patterns, either tidally or by secular interaction. In this context, the situation is different whether the perturbing companions are bound or just passing stars. In any case, dynamical studies (often specific to each system) can greatly help constraining the configuration and the past history of these systems.

Samples of line-of-sight velocities and metallicities for hundreds individual red giant branch stars in Milky Way satellite galaxies have been obtained in the recent past thanks to wide-area multi-object spectrographs on 8 m–10 m class telescopes. These samples have greatly improved our knowledge of the large scale metallicity properties and the internal kinematics of the Milky Way satellites, uncovering in several of these systems the presence of multiple stellar components, velocity gradients and allowing more accurate mass determinations.

With the current instrumentation this kind of studies are already challenging at the outskirts of the Local Group, limiting the variety of galaxy types and environments that we can explore at a similar degree of detail.

With its 42 m diameter, the European Extremely Large Telescope (E-ELT) represents the project for the largest ground-based optical-infrared telescope in the world. In this contribution I discuss results from simulations I have carried out on the feasibility of intermediate resolution spectroscopic surveys in the near-infrared CaII triplet region for large samples of individual red giant branch stars in galaxies at the outskirts of the Local Group and beyond.

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.

Using simplificative assumptions, we show that a redundant configuration of diluted apertures should permitan easier exoplanet detection than a non-redundant one. This result assumes that after coronagraphy theplanet appears over an uniform background whose statistical fluctuation is the unique source of noise. Thedetection is made using a matched filter, cross-correlating the observed image with the telescope array PSF.In that case, the relevant parameter appears to be the integral of the modulus squared of the aperture MTF.

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?"

Recent observations show that the number of stars with very lowmetallicities in the dwarf spheroidal satellites of the Milky Way islow, despite the low average metallicities of stars in these systems. Weundertake numerical simulations of star formation and metal enrichmentof dwarf galaxies in order to verify whether this result can bereproduced with ”standard” assumptions. The answer is likely to benegative, unless some selection bias against very low metallicity starsis present in the observations.

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.

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.


We present the Far Infrared Telescope project submitted to the micro satellite programme of CNES and initially combined to a γ raymission. Millimeter wave emission from MeV-electrons is now wellknown, and on very few occasions non solar dedicated γ raydetectors have revealed emission from electrons at still higherenergies. The combination of two diagnostics: relativisticelectrons-synchrotron radiation in the far infrared and Bremsstrahlungat γ ray would probe electrons at energies above 10 MeV with100 ms time resolution, yielding unique information on the yet unknownhigh energy cut-off of the electron spectrum, and on the responseof the high photosphere to energy input during flares. We emphasizethe opportunity to observe solar flares in far infrared bands andto test uncooled detectors at the ground based station dome C in Antarctica.


Extrasolar planet searches blossomed and prospered under the auspices of the radial velocity method. However, efficient as it is, it can misinterpret a periodic signal created by stellar phenomena as being originated from a planet. The most common of these is the presence of a cold spot, frequent in active stars. Here we review the representative cases of HD 166435, GJ 674 and TW Hya and the different methods used to pinpoint the spots' presence. We finish by underlining the importance of infrared measurements, as done in the TW Hya campaign, as a way of reducing the effect of spots on radial velocity measurements to a negligible level.

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 discuss the properties of extrasolar planets inferred fromobservations and theoretical models. We show that COROT should be ableto usefully constrain the albedos of extrasolar planets with shortorbital periods, given levels of stellar variability close to that ofthe Sun. We sketch possible strategies for observational astrophysicalprograms using high contrast imaging.

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.

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.