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.

BOOTES-1B and BOOTES-2 were first to follow-up the Swift GRB 080605.Observations started 44 s after the GRB trigger, discovering the optical afterglow withthe brightness of R = 14.7. A power-law decay with anα = 1.27 ± 0.04 was observed during the first ~600 s after thetrigger.

Chromospheric evaporation suggests the mass upflows from chromosphere to corona after the electron heating at the chromosphere during the solar flares. It takes place at the rising phase, and has a typical timescale about 100 s and a typical speed about 300–400 km s-1. Such characteristics are well observed as the blueshift at the spectral lines. By the way, the facts of the high-frequency cutoff negatively drifting on the radio dynamic spectra and the hard X-ray footpoint source motions along the loop legs are also thought to be the signatures of the chromosphere evaporation. In this paper, we show the observational evidences of the chromospheric evaporation at radio, EUV and X-ray emissions.

This paper discusses numerical simulations performed in order tobetter understand the dynamics of various physical processes present in theradiative regions of stars. Those processes includesemi-convection, Eddington-Sweet meridional circulationand anisotropic turbulence. The impact of some of those results onevolutionary models is also discussed.


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.

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 explore the problems of determining the abundance of Si in a numberof hot Ap stars.

Atomic diffusion has been suggested to play a significant role in a large variety of CP stars to reproduce observations. In this paper I will briefly present the physics included in the self-consistent models that include atomic diffusion and radiative accelerations. I will discuss their effect on the evolution and on the internal structure of Pop I and Pop II stars, as well as the effect on the predicted surface abundances. I will also present the effect on cluster age determination.

We present the Mirror Advanced technology Coronagraph (MAC) as a new generation solar telescope to be put at suitable high altitude coronal sites in order to resolve modern problems of solar physics, like the origin of the heating of the chromosphere and of the corona, the analysis of the mesospheric layers of the solar atmosphere and the effects of shearing the photospheric magnetic fields on the dynamics of the upper coronal layers.

We use numerical simulations to study the dynamical effect of substructure inCold Dark Matter (CDM) halos on stellar galactic disks. Substructure halos withmasses, densities and orbits derived from high-resolution cosmological CDMsimulations play only a minor dynamical role in the heating of the disk overseveral Gyrs. This is because the orbits of dark satellites in CDM halos seldomtake them near the disk, where their tidal effects are greatest. The mostnoticeable effects of substructure in our simulation may be traced to the mostmassive sub-halo and include: (i) the forcing of short-lived stellar warps in thedisk as a result of tidal shocks that arise during each pericentric passage, and(ii) the tilting of the disk caused by the orbital decay of the satellite. These results imply that substructure might not preclude virialized CDM halos from being acceptable hosts of thin stellar disks like that of the Milky Way, and that the ubiquity of minor stellar warps may be associated with the recurrent tidal influence on the disk of the most massive substructure halos.


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.


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.

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 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.

We present a Monte Carlo (MC) radiative transfer code for complex three dimensional dust distributions and include transiently heated PAH. The correctness of the code is confirmed by comparison with benchmark results. The method makes use of the parallelization capabilities of modern vectorized computing units like graphic cards. The computational speed grows linearly with the number of graphical processing units (GPU). On a conventional desktop PC, our code is up to a factor 100 faster when compared to other MC algorithms. As an example, we compute the dust emission of proto-planetary disks. We simulate how a mid-IR instrument mounted at a future 42 m ELT will detect such disks. Two cases are distinguished: a homogeneous disk and a disk with an outward migrating planet, producing a gap and a spiral density wave. We find that the resulting mid-IR spectra of both disks are almost identical. However, they can be distinguished at those wavelengths by coronographic, dual-band imaging. Finally, the emission of PAHs exposed to different radiation fields is computed. We demonstrate that PAH emission depends not only on the strength but also strongly on the hardness of the radiation, a fact which has often been neglected in previous models. We find that hard photons (>20  eV) easily dissociate all PAHs in the disks of T Tauri stars. To explain the low, but not negligible detection rate (<10%) of PAHs in T Tau disks, we suggest that turbulent motions act as a possible path for PAH survival.

Supersymmetry (SUSY) is a theoretically attractive scenario for physics beyond the Standard Model which provides a suitable Dark Matter candidate in case R-parity is conserved. If SUSY is realized at the TeV scale, as favored by several arguments, it will be accessible at the Large Hadron Collider (LHC) at CERN within the first few years of data taking. We present search strategies for generic SUSY models with R-parity conservation with the ATLAS detector at the LHC. These inclusive search strategies are based on signatures including missing transverse momentum from undetected neutralinos, multiple jets and leptons or b and tau jets. We show the corresponding discovery reach for the first fb-1 of ATLAS data and discuss possible measurements needed to extract the masses of SUSY particles including the undetected neutralino.

Infrared spectroscopy in the mid- and far-infrared provides powerful diagnostics for studying the emission regions in active galaxies. The large variety of ionic fine structure lines can probe gas conditions in a variety of physical conditions, from highly ionized gas excited by photons originated by black hole accretion to gas photoionized by young stellar systems. The critical density and the ionization potential of these transitions allow to fully cover the density-ionization parameter space. Some examples of line ratios diagrams using both mid-infrared and far-infrared ionic fine structure lines are presented. The upcoming space observatory Herschel will be able to observe the far-infrared spectra of large samples of local active galaxies. Based on the observed near-to-far infrared emission line spectrum of the template galaxy NGC 1068, are presented the predictions for the line fluxes expected for galaxies at high redshift. To observe spectroscopically large samples of distant galaxies, we will have to wait for the future space missions, like SPICA and, ultimately, FIRI.

The difficult goal of directly detecting a planet around a star requiresto cancel as much as possible the stellar light.Since the first proposal by Bracewell of a nulling interferometer, where thestar is put on a central dark fringe, several interferometricconfigurations have been presented in order to improve the quality ofthe rejection, especially to avoid the leaks due to the finite angular dimensionof the stellar disk, resolved by the interferometer. In the Bracewell interferometer, the behaviour of the nulling efficiency vs the angular distance θ to the star is as (1-cosθ)∝ θ2. One goal is to increase the exponent of the term θn whichgives the cancellation efficiency. I present one method to define configurations of telescopes positions, sizes and phase-shift that canachieve any given power of θ. The principle is based on a peculiar property foundby Prouhet of a partition into two sets of the integers, done according to the Thué-Morse sequence.2L telescopes regularly spaced on a line, are distributed into two groups, following their rankin the Thué-Morse sequence and, to the telescopes of one of the groups, is applied a π phase shift. The result is a fractal-like distribution of the telescopes where redundancy is minimum andwhose interferometric combination produces a very efficient nulling in θ2L.I first examine 1-D patterns of identical telescopes, then extend the method to 2-D configurations, then show that the lattercan be used to define 1-D arrays of non identical telescopes, according to some algebra of interferometers. The generalizationto arrays where the phase shift between n groups of telescopes is 2kπ/n is finally proposed.

Gravitational settling and microscopic diffusion affects the main sequence lifetimes, main sequence turn-off luminosities and temperatures of metal-poor halo stars. As a result, the inclusion of diffusion in the stellar evolution models has important consequences for age determinations of old stars. In contrast, diffusion has little impact on the post-main sequence evolution of metal-poor stars. Observations of the heavy element abundances in turn-off and giant branch stars in the globular cluster NGC 6397 suggest that diffusion occurs in metal-poor stars, but that the diffusion must be inhibited by turbulent mixing.

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.