The atomic (microscopic) diffusion of individual elements in stellar interiors and atmospheres lead to their accumulation or depletion in specific layers. The selective radiative accelerations on individual elements, which work in opposition to the effects of the pressure and thermal gradients, have important consequences. When acting on elements like iron or nickel, which are important contributors to the opacity in some stellar layers, the resulting overabundance can lead to global macroscopic effects, like extra convective zones or wave excitation by kappa mechanism. The competition between atomic diffusion and independent hydrodynamical processes including turbulent (macroscopic) diffusion has been extensively studied in previous years using parametrized computations. An important macroscopic consequence of atomic diffusion was however ignored: the double-diffusive mixing, also referred to as fingering or thermohaline convection, directly induced by μ-gradient inversion created by local heavy element accumulation. Taking this process into account will modify the studies of the element abundance variations inside stars and in their atmospheres.

The Submillimetron is the international project of the spacetelescope for full sky survey in submillimeter region 0.15-1.5 mmusing facilities of the Russian segment of the InternationalSpace Station (ISS). A free flying module for the project isunder development in corporation Energia. Periodic docking ofthe module to the ISS gives possibility to combine low cost withreliability, refilling, repairment and maintenance. The conceptof the telescope combines a 0.6 m mirror cooled to liquid heliumtemperature with a novel type of microbolometers arrays developedat Chalmers University (Sweden). This combination gives uniquepossibility to realize background limited sensitivity about10-18 W/Hz-1/2 in the spectral minimum of theextraterrestrial background near frequency 1 THz between peaks ofgalactic dust emission and CMB. The angular resolution of theinstrument is about 1 arcmin, field of view ~1°.

We examine the implications for the distribution of extrasolar planets based on the null results from two of the largest direct imaging surveys published to date. Combining the measured contrast curves from Masciadri et al.  (2005) and Biller et al.  (2007), we consider what distributions of planet masses and semi-major axes can be ruled out by these data, based on Monte Carlo simulations of planet populations. We can set the following upper limit with 95% confidence: the fraction of stars with planets with semi-major axis between 20 and 100 AU, and mass above 4 MJup, is 20% or less. Also, with a distribution of planet mass of $\frac{{\rm d}N}{{\rm d}M} \propto M^{-1.16}$ in the range of 0.5–13 MJup, we can rule out a power-law distribution for semi-major axis ($\frac{{\rm d}N}{{\rm d}a} \propto a^{\alpha}$) with index 0 and upper cut-off of 18 AU, and index –0.5 with an upper cut-off of 48 AU. For the distribution suggested by Cumming et al.  (2008), a power-law of index –0.61, we can place an upper limit of 75 AU on the semi-major axis distribution.


IRAN is a method of beam-combination in thehypertelescope imaging technique recently introduced byLabeyrie in optical interferometry. We propose to observe the interferometric image in the pupil plane, performing multi-axial pupil plane interferometry. Imaging is performed in a combined pupil-plane where the point-source intensity distribution (PSID) tends towards apseudo Airy disc for a sufficiently large number of telescopes. The image is concentrated into the limited support of the output pupil of the individual telescopes, in which the object-image convolution relation is conserved. Specific deconvolution algorithms have been developped for IRAN hypertelescope imagery, based upon Lucy-like iterative techniques. We show that the classical (image plane) and IRAN (pupil plane) hypertelescope imaging techniques are equivalent if one uses optical fibers for beam transportation. An application to the VLT/VIDA concept is presented.

New 2D dynamical models for carbon-rich and oxygen-rich AGB stars, and red supergiants are presented which include hydrodynamics with gravity and radiation pressure on dust, equilibrium chemistry, time-dependent dust formation, and coupled frequency-dependent Monte Carlo radiative transfer. The simulations reveal a much more complicated picture of the dust formation and wind acceleration of red giants as compared to 1D spherical models. Triggered by non-spherical pulsations or large-scale convective motions, dust forms event-like in the cooler regions above the stellar surface which temporarily receive less radiation from the star, followed by the radial ejection of dust arcs and clumps. These simulations can possible explain recent high angular resolution interferometric IR observations of red giants, which show an often non-symmetric and highly time-variable innermost dust formation and wind acceleration zone. The new wind models are intended to harvest the results of future interferometric mission like Chara, AMBER on the Vlti, and Alma, aiming to provide the physical answers of the scientific questions arising from these new instruments.

We present here the latest results from experimental studies aiming at measuring the Mass Absorption Coefficient (MAC) of interstellar silicate dust analogues at low temperatures in the far infrared and submillimetre domains which are necessary for the analysis of astronomical data. These results show that above 100 μm, the MAC of amorphous silicate nano-grains has a complex dependence with the grain temperature and with the wavelength. This has to be considered when interpreting astronomical observations to avoid errors on the derived parameters such as the dust mass and its physical and chemical properties.

Stars constitute undoublty one of the elementary blocks of the Universe and play as such a central role in determining forinstance its chemical evolution. They can be seen as modern physics laboratory from which fundamental processes as diverse as atomic physics or turbulence can be studied and understood. Being able to model accurately their structure, dynamic and evolution is thus of fundamental importance and is the subject of intense research. In this short lecture we will first discuss the basic equations and processes, such as convection, turbulence, rotation, instabilities and dynamo action that are at the origin of the magnetic field observed in stars. We will then present some of the numerical simulations in three dimensions performed in recent years to model such complex objects and their nonlinear behavior, focussing mainly on results obtained with the anelastic spherical harmonic (ASH) code. Using the Sun as a reference star, we wish to gain insight the various magnetohydrodynamical processes that shape its large scale dynamics and magnetism, such as the Reynolds and Maxwell stresses, and the ω and α-effects. We will then extend our study to other stars, such as young Suns, massive stars or evolved RGB stars in order to identify which processes are at the origin of their significantly different dynamics.

We report a preliminary study of the main focal plane instrumentfor the IRAIT telescope, currently being built atINAF-Astronomical Observatory of Teramo. The basic requirementsare those of a remotely-controlled camera aimed to perform 10- and20-μm photometry from Dome-C in the standard bandpasses N andQ. Starting from the site properties and the science goals, themain components of AMICA (Antarctic Mid-Infrared CAmera) aredescribed: a Si:As BIB array detector, sensitive in the range 2–28 μm; a fully reflective optical design; a cryostat modified inorder to work at the extreme environmental conditions of theantarctic plateau; a cryocooler maintaining the operatingtemperature of 4.2 K without external intervention; an automatizedand flexible control electronics.
AMICA is designed to fully exploit the unique mid-infrared observing conditions at Dome-C.


The recent discovery of microscopic grains of presolar origin in primitive meteorites has opened a new field of astrophysics where scientists from different disciplines, from nuclear physics to astronomy, chemistry and mineralogy, are required to work together. In this inter-disciplinary field information on the composition of stars is obtained through laboratory analysis of meteoritic rocks. We review the main features of the composition of presolar SiC and oxide grains that are believed to have originated in Asymptotic Giant Branch (AGB) stars. High-precision laboratory measurements of the isotopic composition of these types of presolar grains represent the most detailed record of the composition of AGB stars, and thus a major constraint for the theoretical models of these stars. In particular, the CNO and Al/Mg compositions can set constraints on extra-mixing processes in red giant and AGB stars. The composition of heavy elements produced by slow neutron captures (s-process) yields a variety of information on the grain parent stars, including their masses and the way neutron sources operate.


The signature of activity in general, and of stellar magnetic spots in particular, is present in every measurements, including interferometric ones. Indeed, stellar spots can be found on many stellar surfaces, their size and number varying according to their host's magnetic field and rotational velocity. To correctly determine stellar parameters, it is thus necessary to determine and extract stellar activity's signals. Interferometric observables are disturbed by activity, and this observing technique thus constitutes a good way of probing stellar surface. However, magnetic spots sometimes mimic other phenomenon, like a transiting exoplanet. In that case, the combination of several observing techniques, like photometry and interferometry, is mandatory to extract the planetary signal from the spot's one, and then characterize the exoplanet.

We review the investigation of Super-Earths. After defining this categoryof planets, we briefly defend the paradigm that they may be good targets forthe search of Life, since they may be abundant and all terrestrial conceptsare valid for them.We then describe the scientific benefits of their characterizationby analyzing (by spectroscopy and polarimetry) the light they reflect fromthe parent star. We finally compare the performances of space missions and Dome Capproaches.

It was Zel'dovich who first clearly realized the importance ofquantum vacuum fluctuations in connection with cosmology. Sincethen, this issue has been more a problem than a solution, even ifthe acceleration of the universe expansion could, in principle, beeasily explained by resorting to it. We have calculated thosecontributions in a number of different models. Under some specificconditions, the results look promising, although a generalacceptable solution looks still far from reach.

I review studies of the hot gaseous medium in and around nearbynormal disk galaxies, including the Milky Way. This medium represents a reservoir of materials required for lasting star formation, a depository of galacticfeedback (e.g., stellar mass loss and supernovae), and an interface between the interstellar and intergalactic media. Important progress has been made recently with the detection of X-ray absorption lines in the spectra of X-ray binaries and AGNs.The X-ray absorption line spectroscopy, together with existing X-rayemission and far-UV O iv absorption measurements now allowsfor the first time to characterize the global spatial, thermal, andchemical properties of hot gas in the Galaxy. The results aregenerally consistent with those inferred from X-ray imaging of nearby edge-on galaxies similar to the Milky Way.Observed diffuse X-ray emitting/absorbing gas doesnot extend significantly more than ~10 kpc away from galactic disks/bulges, except in nuclear starburst or very massive galaxies. The X-ray cooling rate of this gas is generally far less than the expected supernova mechanical energy input alone. So the bulk of the energy is “missing”. On the other hand, evidence for alarge-scale (≲ 102 kpc) hot gaseous halo around the Milky Way to explain varioushigh-velocity clouds is mounting. The theoretical argument for ongoing accretion of intergalactic gas onto disk galaxies is also compelling. Idiscuss possible solutions that reconcile these facts.In particular, large-scale hot gaseous halos appear to be low inmetallicity, hence X-ray emission. The metal enrichment in theintergalactic medium may be substantially non-uniform; fast-cooling clumps ofrelatively high metallicity may have largely dropped out and may partly account for high-velocity clouds. In addition, ongoing galactic mechanical energy feedbackis likely important in balancing the cooling of the halos and may bestrong enough to produce galactic winds in bulge-dominated galaxies.

In this work the full orthogonal splitting of Bel andBel-Robinson tensors in a four dimensional spacetime is calculated. We also present the orthogonal splitting of the covariant divergence of Bel-Robinson tensor in vacuum and use the resulting expressions (dynamical laws of superenergy in vacuum) to introduce the concept of intrinsic superenergy radiative state. It is hoped that these results will contribute to the long-standing question of the physical interpretation of the Bel and the Bel-Robinson tensors. 


Multi-wavelength studies of M supergiants have revealed atmospheric structures with a large range of spatial and temporal scales. Focusing on Betelgeuse, these scales and their perplexing connections from the photosphere to the interstellar medium are reviewed. Of particular current interest is the dynamic origin of the ubiquitous and relatively dust-free mass loss. Is it multiple plumes of convection driven ejecta, episodic ejection of molecular reservoirs, or a more steady and uniform flow? With powerful new facilities such as the VLT and ALMA we may begin to understand the connections and answer such puzzles, but ultimately detailed studies of a sample of M supergiants will be needed to disentangle the physics from the stars’ personalities.

Hypervelocity stars are those that have speeds exceeding the escape speed and are hence unbound from the Milky Way. We investigate a sample of low-mass hypervelocity candidates obtained using data from the high-precision SDSS Stripe 82 catalogue, which we have combined with spectroscopy from the 200-inch Hale Telescope at Palomar Observatory. We find four good candidates, but without metallicities it is difficult to pin-down their distances and therefore total velocities. Our best candidate has a significant likelihood that it is escaping the Milky Way for a wide-range of metallicities.

The high Antarctic plateau is considered as the best observing site on Earth in the sub-mm and mm bands. Dome C is one of the most elevated all-year-round station in this continent. Due to its peculiar location, it is also characterized by low wind speeds and very low precipitable water vapor contents.Some experiments have been brought there since 1995 and some ancillary data have been recorded. We report here the actual status of the site quality knowledge in the sub-mm and mm bands.

The use of specific tracers of the dense molecular gas phase can help to explore the feedback of activityon the interstellar medium (ISM) in galaxies. This information is a key to any quantitative assessmentof the efficiency of the star formation process in galaxies. We present the results of a survey devotedto probe the feedback of activity through the study of the excitation and chemistry of the dense moleculargas in a sample of local universe starbursts and active galactic nuclei (AGNs). Our sample includes also17 luminous and ultraluminous infrared galaxies (LIRGs and ULIRGs). From the analysis of the LIRGs/ULIRGssubsample, published in Graciá-Carpio et al.  (2007), we find the first clear observational evidencethat the star formation efficiency of the dense gas, measured by the LFIR/LHCN ratio, issignificantly higher in LIRGs and ULIRGs than in normal galaxies. Mounting evidence of overabundantHCN in active environments would even reinforce the reported trend, pointing to a significant turnupward in the Kennicutt-Schmidt law around LFIR = 1011L๏. This result has majorimplications for the use of HCN as a tracer of the dense gas in local and high-redshift luminousinfrared galaxies.


The Dome C should benefit from an outstanding atmospheric qualityduring the night due to catabatic wind conditions (wind speed ~ 2 m s-1, r0 ~ 0.3 m). From analytical and numericalsimulations, we show that these seeing conditions are veryadvantageous for high-contrast imaging and coronagraphic search ofexoplanets in the near-IR with adaptive optics (AO): from the DomeC, the planet SNR is 4 times greater than from Mauna-Kea.
For these reasons, the Dome C seems to be the natural site for aPlanet-Finder consisting in a 2–8 m (possibly off-axis) monolithictelescope equipped with a fast and extreme AO (f ~ 1–2 kHz, f ~ cm), a low-aliasing wave-front sensor (WFS), acoronagraph and a speckle-noise subtraction. In these optimalconditions, a 3.6 m and a 8.2 m-telescope can respectively detect aJupiter-size and an Earth-size planet at 10 pc in 10h in J band. Lastly, a 15–30 m ELT located at the Dome C could performfast spectral analysis of Earth-like planets for biomarkersearching.

Dutch astronomer S.R. Pottasch, who was appointed as one of the two first Editors-in-Chief of A&A together with J.L. Steinberg, recalls the events that led to the creation of the first European astronomy journal. This account is based on the author’s notes and documents and also on an article relating ESO’s early history written by A. Blaauw and published in The ESO Messenger No. 60, pp. 23–34 (1990). C. Bertout added footnotes giving a few biographical details about the actors.