Multi-epoch, high-resolution (R ∼ 50 000) optical spectrosco-py of the O-type (O9 III – IV) star HD 152246 suggests that it is a triple system where a close inner pair (Aa–Ab) with a circular orbit and a period of 6 days is in a 53–d eccentric orbit (e = 0.68) with a third component Ac. The mass ratios for the inner and outer system are 0.10 and 0.96, respectively. The strengths of various He lines classify Aa and Ac as late O-type stars while Ab is invisible in our spectra.

The PAMELA satellite-borne experiment was launched from the Baikonur launch site on the 15th of June 2006. Since July 2006 it is daily delivering to ground 16 GBytes of data. The instrument is composed by a magnetic spectrometer, a time-of-flight system, a silicon-tungsten electromagnetic calorimeter, a neutron detector and anticoincidence scintillators. The primary scientific goal is to searching for evidence of dark matter particle annihilations studying antiparticles fluxes. Preliminary results concerning antiproton-proton and positron-electron ratios are presented.

We focus our analysis on an event which occurred at the W-limb on May 30, 2003. The dynamical behavior of the filament, including damped oscillations, was investigated with the CDS and EIT (SoHO) experiments, as well as with Hα filtergrams (movies). The eruptive phase is analyzed taking into account the approximate phasing with other eruptive phenomena occurring at the same time or before, called homologous flares and eruptions.

This review covers a variety of topics related to the properties of Pre–Main Sequence stars in star forming regions, young clusters and associations. Some recent developments of theoretical models of PMS evolution are discussed, with emphasis on the role of magnetic fields in low-mass stars and their impact on observable quantities. Critical tests on the comparison between model predictions and observations are presented for stars across the mass spectrum. The issue of the formation and early evolution of massive stars is addressed, with emphasis on clustered versus isolated objects. After a brief historical background on the derivation of the Initial Mass Function, current representations of this quantity are discussed. The issue of the duration of the star formation process is dealt with using the results of age dating methods for young stars, mainly based on the property of Lithium depletion during PMS evolution. A recent analysis of the properties of the stellar population of the Orion Nebula Cluster is presented with the resulting IMF and age distributions. Finally, a discussion of recent determinations of the metallicity distribution of young stars in clusters and associations closes the review.

Due to the recent interest shown by astronomers towards the Antarctic Plateauas a potential site for large astronomical facilities, we assistedin the last years to a strengthening of site testing activities in this region, particularly at Dome C. Most of the results collected so far concern meteorologic parameters and optical turbulence measurements based on different principles using different instruments. At present we have several elements indicating that, above the first $20{-}30$ m, the quality of the optical turbulence above Dome C is better than above whatever other site in the world. The challenging question, crucial to know which kind of facilities to build on, is to establish how much better the Dome C is than a mid-latitude site. In this contribution we will provide some complementary elements and strategies of analysis aiming to answer to this question. We will try to concentrate the attention on critical points, i.e. open questions that still require explanation/attention.

Large amounts of invisible matter have been discovered back in 1933 when the Swiss astronomer Fritz Zwicky measured for the first time the velocity dispersion of individual galaxies inside the Coma cluster. Since then, this pioneering observation has been confirmed on scales ranging from galactic radii to cosmological distances. The existence of the so–called astronomical dark matter is now well established. The puzzle lies in the fact that this essential component of the universe is not made of ordinary atoms and electrons. The astronomical dark matter is indeed non–baryonic. Its nature is still an unresolved issue. Many theoretical ideas and proposals have flourished in the past thirty years and yet none of them provides a definite answer. I have the challenging task to introduce the cohort of these dark matter candidates to you. They make up a bestiary of exotic species which have been recently proliferating. Instead of a liste à la Prévert, I will present a tentative classification of the various models.

Feedback processes are now realized to hold the key to our understanding ofgalaxy formation and evolution, particularly during the early epochs that we commonly dub as the Cosmic Dawn. We propose and discuss a classification in which three broad feedback classes (radiative, chemical and mechanical) can be identified. We also discuss the underlying physics for each of these feedbacks and point outtheir importance in different cosmological contexts. Finally, the link between mechanical feedback and the heavy element transport is explored with the aim of understanding the cosmic metal budget and the enrichment history of the intergalactic medium.

We have chosen the name of GYES, one of the mythological giants with one hundred arms,offspring of Gaia and Uranus, for our instrument study of a multifibre spectrograph forthe prime focus of the Canada-France-Hawaii Telescope. Such an instrument could provide anexcellent ground-based complement for the Gaia mission and a northern complement to theHERMES project on the AAT. The CFHT is well known for providing a stable prime focusenvironment, with a large field of view, which has hosted several imaging instruments, buthas never hosted a multifibre spectrograph. Building upon the experience gained at GÉPIwith FLAMES-Giraffe and X-Shooter, we are investigating the feasibility of a highmultiplex spectrograph (about 500 fibres) over a field of view one degree in diameter. Weare investigating an instrument with resolution in the range 15 000 to 30 000, whichshould provide accurate chemical abundances for stars down to 16th magnitude and radialvelocities, accurate to 1 km s-1 for fainter stars. The study is led byGÉPI-Observatoire de Paris with a contribution from Oxford for the study of thepositioner. The financing for the study comes from INSU CSAA and Observatoire de Paris.The conceptual study will be delivered to CFHT for review by October 1st 2010.

We review the main results of our previous works, in which we have investigated the development of the Kelvin-Helmholtz (KH) instability in the transitional regime from sub-magnetosonic to super-magnetosonic by varying the solar wind velocity, in conditions typical of those observed at the Earth’s magnetopause flanks. In super-magnetosonic regimes, we show that the vortices produced by the development of the KH instability act as an obstacle in the plasma flow and may generate quasi-perpendicular magnetosonic shock structures extending well outside the region of velocity shear.

We discuss the various post-main sequence phases of massive stars,focusing on Wolf-Rayet stars, Luminous Blue Variables, plus connectionswith other early-type and late-type supergiants. End states for massive stars are also investigated, emphasising connections between Supernovae originating fromcore-collapse massive stars and Gamma Ray Bursts.

We present the results of an all sky survey for binary systems among the massive stars that we made with the HST Fine Guidance Sensors. The sample of 225 stars is comprised mainly of Galactic O- and B-type stars and Luminous Blue Variables, plus a few luminous stars in the LMC. The FGS TRANS mode observations are sensitive to detection of companions with an angular separation of 0.01–1 arcsec and brighter than △m = 5 mag. The FGS observations resolved 52 binary and 6 triple star systems and detected partially resolved binaries in 7 additional targets, yielding a companion detection frequency of 29%. We also gathered literature results on the numbers of close spectroscopic binaries and wider astrometric binaries among the sample. These results confirm the high multiplicity fraction. The period distribution is essentially flat in increments of log P, although there remains an observational gap in detections for periods of years and decades.

This report aims to provide a summary of the status of our Antarctic Submillimetre Telescope (AST) project up to date. It is a very new project for Antarctic astronomy. Necessary prerequisites for a future deployment of a large size telescope infrastructure have been tested in years 2007 and 2008. The knowledge of the transmission, frost formation and temperature gradient were fundamental parameters before starting a feasibility study. The telescope specifications and requirements are currently discussed with the industrial partnership.

Abundances anomalies and helioseismology provideconstraints on the turbulent transport of chemical species in stellar radiativezone. We use these constraints to derive upper bounds on thevelocity and lengthscale of the vertical turbulent motions.We also present numerical simulations showingthat a strong anisotropy between horizontal and vertical motionscould help understand the observed transport.

The Large Magellanic Cloud (LMC) is the closest large satellite of the Milky Way (MW) and the first step of the extragalactic distance scale, hence knowing the distance to the LMC and its three-dimensional structure contributes to the definition of the entire cosmic distance ladder. RR Lyrae stars are old objects which trace the halo of the LMC. They can be used as distance indicators because they follow a period-luminosity-metallicity (PLKsZ) relation in the Ks passband. The purpose of this study was the derivation of a new PLKsZ relation for RR Lyrae stars in the LMC based on the multi-epoch Ks photometry obtained by the VISTA survey of the Magellanic Clouds system (VMC, Cioni et al. 2011).

Astronomy is in a golden age of discovery of the new, with a growingappreciation from astrophysics that physics has studied so far analmost insignificant fraction of reality. This golden age is enabledby technology, with next generation technologies approaching theGiga-euro/dollar investment level. This forces a strategic view of relativestrengths in the past, and strategies for future developments. Some ofthese may transcend traditional wavelength classifications.


One of the key aspects of the upcoming Ultra-Fast Flash Observatory (UFFO) pathfinder forGamma Ray Bursts (GRBs) identification is the UFFO Burst Alert & Trigger Telescope(UBAT). The scientific propose of UBAT is to detect and locate as fast as possible theGRBs in the sky. This is achieved by using a coded mask aperture camera scheme with a widefield of view (FOV) and selecting a X-ray detector of high quantum efficiency and largedetection area. This X-ray detector of high quantum efficiency and large detection area iscalled the UBAT detector. The UBAT detector consists of 48 × 48 Yttrium Oxyorthosilicate(YSO) scintillator crystal arrays and Multi Anode Photomultiplier Tubes (MAPMTs), analogelectronics equipped with ASIC chips, digital electronics equipped with Field ProgrammableGate Array (FPGA) chips, and a mechanical structure that supports all components of theUBAT detector. The total number of the pixels in the UBAT detector is 2304, and the totaleffective detection area is 191 cm2. We will present the design andconstruction, and performance of the UBAT detector including the responses of the UBATdetector to X-ray sources.

This article is intended to be used as an introduction to the problem of protoplanetary dust aggregation. The basic concept of dust aggregation and its description by Smoluchowski's equation are presented. Analytic solutions to Smoluchowski's equation are explored which show some characteristics of the more general solutions, such as self-similarity and scaling behavior. The physics of dust aggregation is treated through interaction forces between the particles and empirical data on sticking efficiencies and particle morphologies in dust-dust collisions. Aggregate morphologies are described by the fractal concept, and its implications for collision cross sections and collision velocities are discussed. Theoretical and experimental work on collision-induced restructuring and fragmentation of fractal and non-fractal dust aggregates is presented. Finally, the latest modelling approaches for protoplanetary dust growth are discussed.

The analysis of mid-IR emission suggests that a population of PAH-related very smallgrains containing a few hundreds of atoms are present in the deep regions of molecularclouds,although no specific species has been identified yet. In this review,we discussseveral candidates for these grains: neutral and ionised PAH clusters and complexes ofPAHs with Si atoms. The theoretical modelling of the properties of such molecularcomplexes or nanograins is a challenging task. We first present an overview of quantumchemistry derived models which can be efficiently used on-the-fly in extensive sampling ofthe potential energy surfaces,as required by structural optimization,classical moleculardynamics or Monte Carlo algorithms. From the simulations,various observables can bedetermined,such as the binding energies,finite temperature IR spectra,nucleation andevaporation rates. We discuss the relevance of those candidates in the molecular cloudsphotodissociation regions and propose constrains and perspectives for the nature and sizeof those very small grains.

Recent ultra-high precision observations of eclipsing binaries, especially data acquired by the Kepler satellite, have made accurate light curve modelling increasingly challenging but also more rewarding. In this contribution, we discuss low-amplitude signals in light curves that can now be used to derive physical information about eclipsing binaries but that were unaccessible before the Kepler era. A notable example is the detection of Doppler beaming, which leads to an increase in flux when a star moves towards the satellite and a decrease in flux when it moves away. Similarly, Rømer delays, or light travel time effects, also have to taken into account when modelling the supreme quality data that is now available. The detection of offsets between primary and secondary eclipse phases in binaries with extreme mass ratios, and the observation of Rømer delays in the signals of pulsators in binary stars, have allowed us to determine the orbits of several binaries without the need for spectroscopy. A third example of a small-scale effect that has to be taken into account when modelling specific binary systems, are lensing effects. A new binary light curve modelling code, PHOEBE 2.0, that takes all these effect into account is currently being developed.