Thick layers of warm, low density ionized hydrogen (i.e., the warm ionized medium or WIM) in spiral galaxies provide direct evidence for an interaction between the disk and halo. The wide-spread ionization implies that a significant fraction of the Lyman continuum photons from O stars, produced primarily in isolated star forming regions near the midplane and often surrounded by opaque clouds of neutral hydrogen, is somehow able to propagate large distances through the disk and into the halo. Moreover, even though O stars are the source of the ionization, the temperature and ionization state of the WIM differ significantly from what is observed in the classical O star H ii regions. Therefore, the existence of the WIM and observations of its properties provide information about the structure of the interstellar medium and the transport of energy away from the midplane as well as place significant constraints on models.

Observations of the interstellar medium (ISM) reveal its fractalstructure over a large range of scales. The quantitative description shows that the ISM consists mainly of surfaces, so that the stellar UV-radiation can deeply penetrate intothe ISM and in consequence dominates its physical and chemical conditions. Thus, the bulk of the ISM can be identified as photon dominated regions (PDRs). A simple model with the proper fractal characteristics is that of an ensemble of spherical clumps with a power-law mass spectrum and a power-law mass-size relation. Hence, we model the FIR line emission of the molecular gasby the integrated emission of such an ensemble, calculating the emission of individual clumps with the KOSMA-τ PDR code. This clumpy PDR-model, with observationally constrained parameters, is fitted to the CO, [C i], and [O i] emission along the Galactic plane as observed by the FIRAS instrument abord the COBE satellite. The FIR line intensity distribution with Galactic longitude is reproduced within factors of about 2. The predicted [C ii] 158 μm line intensity and FIR continuum emission also coincide with the observations.

This review presents a general overview of the magnetic fields foundin main sequence A and B stars, and of some of the phenomenaassociated with this magnetism. An attempt is made to place theobserved magnetic fields into an evolutionary context.

With the first light of COROT, the preparation of KEPLER and the future helioseismology spatial projects such as GOLF-NG, a coherent picture of the evolution of rotating stars from their birth to their death is needed. We describe here the modelling of the macroscopic transport of angular momentum and matter in stellar interiors that we have undertaken to reach this goal. First, we recall in detail the dynamical processes that are driving these mechanisms in rotating stars and the theoretical advances we have achieved. Then, we present our new results of numerical simulations which allow us to follow in 2D the secular hydrodynamics of rotating stars, assuming that anisotropic turbulence enforces a shellular rotation law. Finally, we show how this work is leading to a dynamical vision of the Hertzsprung-Russel diagram with the support of asteroseismology and helioseismology, seismic observables giving constraints on the modelling of the internal transport and mixing processes. In conclusion, we present the different processes that should be studied in the near future to improve our description of stellar radiation zones.

Assuming that the extended emission (EE) with broad dynamic range is a common property ofshort duration bursts, we propose a two-jet model which can describe both short mainepisode of hard spectra emission, specific for short bursts, and softer spectra EE by thedifferent off axis position of the observer. The model involves a short-duration jet,which is powered by heating due to νν̅ annihilation, and a long-lived Blandford–Znajek (BZ)jet with a significantly narrow opening angle. We also discuss observational tests oftwo-jet model.

Within the key project “Herschel M 33 extended survey” (HerM33es), we are studying the physical and chemical processes driving star formation and galactic evolution in the nearby galaxy M 33, combining the study of local conditions affecting individual star formation with properties only becoming apparent on global scales. Here, we present recent results obtained by the HerM33es team. Combining Spitzer and Herschel data ranging from 3.6 μm to 500μm, along with H i, Hα, and GALEX UV data, we have studied the dust at high spatial resolutions of 150 pc, providing estimators of the total infrared (TIR) brightness and of the star formation rate. While the temperature of the warm dust at high brightness is driven by young massive stars, evolved stellar populations appear to drive the temperature of the cold dust. Plane-parallel models of photon dominated regions (PDRs) fail to reproduce fully the [C ii], [O i], and CO maps obtained in a first spectroscopic study of one 2′ × 2′ subregion of M 33, located on the inner, northern spiral arm and encompassing the H ii region BCLMP 302.

The Antarctic plateau has superb astronomical seeing above aturbulent boundary layer. This layer has a thickness of between tensof metres and a few hundred metres, depending on the site. We aredeveloping a sonic radar, SNODAR, to measure the turbulence in theboundary layer from 10 to 50 m, and, in particular, to measurethe height of the boundary layer to an accuracy of 1 m.Commercial sonic radars typically have a lower limit of about 10 m, and have 10 m range bins. The results from SNODAR shouldallow a confident assessment of the height at which one must mount atelescope in order to realise the superb free atmosphere seeing fromthe Antarctic plateau, which has been measured at Dome C to be 0.27arcsecs on average, and better than 0.15 arcsecs for 25% of thetime.


We discuss the accuracy for the recovery of mass profiles in simulated dwarf galaxies. We also present cosmologically motivated, high resolution N-body models for two nearby dwarf galaxies: NGC 3109 and NGC 6822. The rotation curves in our models are measured using standard observational techniques, projecting velocities along the line of sight of an artificial observer and performing a tilted ring analysis. Our models reproduce the rotation curves of both galaxies, the disk surface brightness profiles as well as the profile of isophotal ellipticity and position angle. We show that non-circular motions combined with gas pressure support and projection effects systematically underestimate by up to 50% the rotation velocity of cold gas in the central ~1 kpc region, creating the illusion of a constant density core.

In-depth analysis of eclipsing binary (EB) observational data collected for several decades can inform us about a lot of astrophysically interesting processes taking place in the systems. We have developed a wide-ranging method for the phenomenological modelling of eclipsing binary phase curves that enables us to combine even very disparate sources of phase information. This approach is appropriate for the processing of both standard photometric series of eclipses and data from photometric surveys of all kind. We conclude that mid-eclipse times, determined using the latest version of our “hi-fi” phenomenological light curve models, as well as their accuracy, are nearly the same as the values obtained using much more complex standard physical EB models.

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.

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.

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.

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.

Betelgeuse, the bright red supergiant (RSG) in Orion, is a runaway star. Its supersonic motion through the interstellar medium has resulted in the formation of a bow shock, a cometary structure pointing in the direction of motion. We present the first 3D hydrodynamic simulations of the formation and evolution of Betelgeuse’s bow shock. We show that the bow shock morphology depends substantially on the growth timescale for Rayleigh-Taylor versus Kelvin-Helmholtz instabilities. We discuss our models in light of the recent Herschel, GALEX and VLA observations. If the mass in the bow shock shell is low (~few  × 10-3M⊙), as seems to be implied by the AKARI and Herschel observations, then Betelgeuse’s bow shock is very young and is unlikely to have reached a steady state. The circular, smooth bow shock shell is consistent with this conclusion. We further discuss the implications of our results, in particular, the possibility that Betelgeuse may have only recently entered the RSG phase.

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.


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.

So as to prepare future observations of terrestrial extrasolar planets liable to shelter life, we attempt to detect the life on the Earth seen as a dot. We use the Moon Earthshine, in which any place reflects the totality of the enlightened part of Earth facing the Moon. Observing from OHP and from ESO, we detected terrestrial chlorophyll in the near infrared, the so-called Vegetation Red Edge, and this detection is larger when forests are present than when an ocean is mainly visible from the Moon. Only if observations are made from a high latitude location, and at some moments in the year, Earthshine can be observed during a large part of the day. During these long observing windows, different “landscapes" are facing the Moon. So the Earthshine corresponding to various parts of our Earth could be studied. Preliminary testing observations have been made at Concordia since the first winterover campaign and the LUCAS experiment has been set up.

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.

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.