We present recent advances on ultra low noise visible detectors at Laboratoire d'Astrophysique de Marseille, photon counting and EMCCD developments in collaboration with Observatoire de haute provence, Laboratoire d'astrophysique de l'observatoire de Grenoble and Laboratoire d'Astrophysique Experimentale (Montreal). After a review of the progress with third generation Image Photon Counting Systems (IPCS), we present the OCAM camera, based on the E2V CCD220 EMCCD, part of the Opticon JRA2 programme, and the CCCP controller, a new controller for the 3DNTT instrument that reduces the clock induced charge of an EMCCD by a factor 10, making it competitive with IPCS detectors for very faint fluxes. We will finally present the RAPID project and the concept of photon counting avalanche photodiode CMOS device (in collaboration with CEA-LETI) which is foreseen to be the ultimate detector for the visible-IR range providing no readout noise, high QE and extremely fast readout.

We present a method to measure the dynamical mass of extrasolar planets in multiple stellar systems with a single aperture from the ground using high-precision relative astrometry. To reach the precision needed, accurate monitoring of the astrometric stability (pixel scale, orientation, and field distortions of the detector) is necessary. Thus, we always observe an astrometric calibration cluster to compare these astrometric criteria with those of our observations. For our first target observed, the binary HD 19994, we achieved a relative precision of 100...150 µas which is sufficient to detect an astrometric companion around the A component down to about 5 MJup.

Using a variety of laboratory analogues and some simple models, Itry to portray the fluid dynamics of very hot stars and disks. By analogy to fluidizedbeds, we may expect the formation of photon bubbles that stir things up intoa sort of turbulence. Because of rotation, the bubbles merge tomake vortices whose presence causes inhomogeneous radiative outflowsand produces spots. These phenomena will allow the Eddington limit to be exceeded and, where the radiative outflows are locally large, mass loss will be encouraged.

As potential progenitors of the Ap stars, the pre-main sequence intermediate mass Herbig Ae/Be stars present us with the opportunity to investigate theearly history of magnetic fields at these masses. Although we have nodirect evidence for the presence of magnetic fields in thesestars (except in one case), many clues for such fields have been identified in the past years. They include active phenomena which areoften attributed to surface magnetic fields. Rotational modulation ofspectral lines formed at the photosphere and in the wind of these starsconstitutes yet another indication for the presence of such fields. Future prospects for the detection and mapping of hypotheticalmagnetic fields in Herbig Ae/Be stars are very encouraging, andin particular spectropolarimetric observations of these stars withinstruments like Espadons on CFHT will allow us to test thehypothesis that magnetic fields similar to those found on Ap starsare indeed present in these pre-main sequence objects.

I briefly outline a new physical interpretation to the average cosmological parameters for an inhomogeneous universe with backreaction. The variance in local geometry and gravitational energy between ideal isotropic observers in bound structures and isotropic observers at the volume average location in voids plays a crucial role. Fits of a model universe to observational data suggest the possibility of a new concordance cosmology, in which dark energy is revealed as a mis-identification of gravitational energy gradients that become important when voids grow at late epochs.

We report in this paper on the current status of the mid-infrared beam combiner of the VLTI: MIDI. We explain the interest of VLTI for this range of wavelentghs and give an overview of the main characteristics of MIDI and present its scientific targets.

The structure of radiative shock waves propagating through partially ionized hydrogen gas in stellar atmospheres is discussed. Basic equations including the radiation transfer and the method of their self-consistent solution are described. The most striking result is that the ratio of the radiative flux to the total energy flux of the shock wave very rapidly enlarges with increasing upstream velocity, so that for Mach number larger than 7, the major part of the shock energy is irreversibly lost due to dissipation processes. The understanding of the “missing temperature”,called microturbulence by the astrophysicists, which appears when we wantto modelling the width of stellar line profiles, is discussed.It is shown that the turbulenceamplification in the atmosphere of a radially pulsating star is not onlydue to the global compression of the atmosphere during thepulsation. Strong shock waves propagating from the deep atmosphereto the very low density layers also play a role in the turbulencevariation, especially when they become very strong i.e., hypersonic.For shocks, the predicted turbulence amplification predicted by classicalmodels is overestimated with respect to stellar observationswhen the compression rate becomes larger than 2 which corresponds to alimit Mach number near 2. Thus, when radiative effects take place, thepresent turbulence amplification theory breaks down. A new approach isrequired.

In October 2000, the GAIA astrometric mission wasapproved as one ofthe next two "cornerstones" of ESA's science programme, with a launchdate target of 2010-12. GAIA will provide positional and radialvelocity measurements with the accuracies needed to produce astereoscopic and kinematic census of about one billion starsthroughout our Galaxy (and into the Local Group), amounting to about1 per cent of the Galactic stellar population. GAIA's main scientificgoal is to clarify the origin and history of our Galaxy, from aquantitative census of the stellar populations. It will advancequestions such as when the stars in our Galaxy formed, when and how itwas assembled, and its distribution of dark matter. The survey aimsfor completeness to V=20 mag, with accuracies of 10 μas at15 mag.

ASAP is a project initiated at the MPIfR which aims at providing a new generation of scientific analysis tools to extract the physical information from the high dynamical range data of current and future instruments. It was motivated by the ALMA project but the concepts and their implementations are applicable to all wavelengths. This presentation is focused on DALIA (Direct Aproach to spectral Line Analysis), a prototype software for forward modeling. It consists of a JAVA graphical user interface through which the user can fit models to observations. The models are stored as binaries and are described by XML files according to a schema. New models developed in any language can thus be easily added to the model database by the user. The different steps of the fit (simulation, evaluation, parameter change) can be executed manually or automatically through an optimization engine. The interface allows the user to have a direct control on the model parameters which can be fixed or constrained. The data to be modeled can be of any type (1D, 2D, 3D, specral, spatial, temporal...) and associations of datasets of different types are supported as long as the axes are identical to those of the model output. In this prototype the FITS format is supported. For spectral synthesis, the spectroscopic data from the molecular databases (Cologne, JPL) are used. This approach is very generic and uses concepts similar to those of the Virtual Observatory. Its integration into the VO would allow astronomers to use the data archives to constrain a model and would permit to store model solutions for each source. These model solutions could thus be easily shared and be improved with the aquisition of new data.

Our Galaxy is pervaded by strong magnetic fields, which, together withthe ordinary matter (made of gas and dust) and the cosmic rays,form the three basic constituents of the interstellar medium.After briefly reviewing our current observational knowledge aboutGalactic magnetic fields, I will address, from a theoretical point of view, the fundamental questionsof their origin and their impact on the interstellar medium.

The Gattini-DomeC project, part of the IRAIT site testing campaign and ongoing since January 2006, consists of two cameras for the measurement of optical sky brightness, large area cloud cover, and auroral detection above the DomeC site, home of the French-Italian Concordia station. The cameras are transit in nature and are virtually identical except for the nature of the lenses. The cameras have operated throughout the past two Antarctic winter seasons and here we present the results obtained from the 2006 winter-time dataset of the wide field “All-sky camera".

The term “magnetosphere” originated historically from early spacecraft measurements of plasma trapped by the magnetic field of earth and other planets. But over the years this concept has also been applied to the magnetically channeled wind outflows from magnetic stars. The review here describes the basic magnetohydrodynamics (MHD) approach used to model such stellar magnetospheres, with emphasis on the central competition between confinement by the magnetic field vs. expansion of the stellar wind outflow. A key result is that, for a star with a dipole surface field B∗, surface radius R∗, and asymptotic wind momentum ${\dot M} v_{\infty}$, this competition can be well characterized by a single “wind magnetic confinement parameter”, $\eta_{\ast} \equiv B_{\ast}^{2} R_{\ast}^{2}/{\dot M} v_{\infty}$. For large η∗, closed magnetic looops can confine parts of the wind up to an Alfvén radius RA ≈ η1/4 R∗, leading to “magnetically confined wind shocks” that might produce the relatively hard X-ray emission seen in some magnetic stars. In rotating stars, RA also roughly characterizes the radius up to which material co-rotates with the underlying star. For the outflowing wind, the associated loss of angular momentum, can lead to spindown in the stellar rotation over a time much shorter than the star's evolutionary timescale. For confined material within RA but beyond the star's Keplerian corotation radius RK, the net centrifugal support against gravity can lead to a “rigidly rotating magnetosphere” composed of accumulating trapped wind. This can provide a natural explanation for the rotationally modulated Balmer line emission observed from magnetic Bp stars. Moreover, magnetic reconnection heating from episodic centrifugal breakout events might explain the occasional very hard X-ray flares seen from such stars. Overall, it seems clear that magnetic fields can play a strong role in confining and channeling such stellar wind outflows, providing a natural explanation for various observational signatures structure and variability in the winds and circumstellar envelopesof massive stars.

We present an overview of SPICA, the Space Infrared Telescope for Cosmology and Astrophysics, a world-class space observatory optimized for mid- and far-IR astronomy (from 5 to  ~210 μm) with a cryogenically cooled  ~3.2 m telescope (<6 K). Its high spatial resolution and unprecedented sensitivity in both photometry and spectroscopy modes will enable us to address a number of key problems in astronomy. SPICA’s large, cold aperture will provide a two order of magnitude sensitivity advantage over current far–IR facilities (λ > 30μm wavelength). In the present design, SPICA will carry mid-IR camera, spectrometers and coronagraph (by JAXA institutes) and a far-IR imager FTS-spectrometer, SAFARI (~34–210 μm, provided by an European/Canadian consortium lead by SRON). Complementary instruments such as a far-IR/submm spectrometer (proposed by NASA) are also being discussed. SPICA will be the only space observatory of its era to bridge the far–IR wavelength gap between JWST and ALMA, and carry out unique science not achievable at visible or submm wavelengths. In this contribution we summarize some of the scientific advances that will be made possible by the large increase in sensitivity compared to previous infrared space missions.

Elliptical galaxies follow a well-known luminosity – metallicity (L − Z) relation, in the sense that more luminous ellipticals are observed to be more metal-rich than less luminous systems. Obviously this is a mass – Z relation, and its interpretation is that less massive galaxies had more significant outflows of metal-enriched gas at an early evolutionary stage. The apparent ellipticity (ϵ) had already been invoked to explain the large scatter in the L − Z relation, but Barazza & Binggeli (2002) observed that the relation between Z and ϵ in cluster dwarf elliptical galaxies (dEs) could even be stronger than the relation with mass. The idea is that outflow of metal-enriched gas preferentially occurs along the minor axis, making ϵ a critical parameter for Z in dwarfs. Here, we test this hypothesis using high-resolution N-body/SPH simulations including chemical feedback of dEs with different flattenings.

In order to optimize the occulting process of a Lyot coronagraph and to provide a high dynamic range imaging, a new kind of occulting disk has been developed at the National Observatory ofRio de Janeiro. A mercury (Hg) drop glued onto an optical window by molecular cohesion and compressed by a pellicle film is used as the occulting disk. The minimum of the superficial tension potential function provides an optical precision (lambda/100) of the toric free surface of the mercury. This process provides a size control for the adaptation to the seeing conditions and to the apparent diameter of a resolved object, and in the case of adaptive optics, to the Airy diameter fraction needed. The occultation is a three dimensional process near the focal plane on the toric free surface that provides an apodization of the occultation. The Hg-Mask coronagraph has been projected for astrometric observations of faint satellites near to Jovian planets and works since 2000 at the 1.6 m telescope of the Pico dos Dias Observatory (OPD - Brazil).

I present observations of shock-processed PAHs and dust in supernova remnants (SNRs).Supernova shocks are one of the primary sites destroying, fragmenting and alteringinterstellar PAHs and dust. Studies of PAHs through supernova shocks had been limitedbecause of confusion with PAHs in background emission. Spitzerobservations with high sensitivity and resolution allow us to separate PAHsassociated with the SNRs and unrelated, Galactic PAHs. In the young SNR N132D, PAHfeatures are detected with a higher PAH ratio of 15–20/7.7 μm than thoseof other astronomical objects, and we suggest large PAHs have survived behind the shock.We present the spectra of additional 14 SNRs observed with Spitzer IRSand MIPS SED covering the range of 5–90 μm. Bright PAH features from 6.2to 15–20 μm are detected from many of SNRs which emit molecular hydrogenlines, indicating that both large and small PAHs survive in low velocity shocks. Weobserve a strong correlation between PAH detection and carbonaceous small grains, while afew SNRs with dominant silicate dust lack PAH features. We characterize PAHs depending onthe shock velocity, preshock density and temperature of hot gas, and discuss PAH and dustprocessing in shocks and implication of PAH and dust cycles in ISM.

Recent results of asteroseismology have been achieved on a growing list of solar-type stars thanks to high precision echelle spectrographs.These results indicates that Doppler measurements are more efficient from the ground than photometry for p-modes detections. A high precision spectrograph dedicated for Doppler asteroseismology based in Dome C will play an important and fundamental step in asteroseismology. Such an instrument coupled to an only 1-m class telescope will be able to reach a very high level of sensibility for p-mode detection on several tens of solar-type stars. Capabilities and expected performances in asteroseismology of a replica of the SOPHIE spectrograph (1.93-m OHP) based in Dome C are presented. Such an instrument is furthermore fully compatible and adapted for polarimetry studies and detection and characterization of extra-solar planets.