In this lecture I present the way stars can be modeled in two dimensions and especially the fluid flows that are driven by rotation. I discuss some of the various ways of taking into account turbulence and conclude this contribution by a short presentation of some of the first results obtained with the ESTER code on the modeling of interferometrically observed fast rotating early-type stars.

Results are presented from studies of the process of plasma acceleration along the current sheet width under different experimental conditions. The behavior of the neutral component is included in the analysis.

Our laboratories have recently calculated a set of collision coefficients characterizing the efficiency of energy transfer between helium and/or hydrogen and a large variety of interstellar molecules. We have considered with molecules ranging from light hydrides, observed by the Herschel Space Observatory, to medium size molecules, observed by mm antennas, to heavy complex organic molecules, observed also in the cm range. We present a review of recent theoretical results obtained in our laboratories, for various kinds of commonly observed molecules.

This paper reviews the various processes that have been proposed to explain the observedtrend of PAH strength with metallicity. It summarizes a study showing that, although PAHdestruction by hard radiation is important in low-metallicity environments, it is notsufficient to explain their paucity. In these systems, the deficiency of their formationmechanism, related to stellar evolution, has to be invoked.

Herschel is the fourth cornerstone mission in the European Space Agency (ESA) science programme. It will perform imaging photometry and spectroscopy in the far infrared and submillimetre part of the spectrum, covering approximately the 55–672 µmm range and thus bridging the traditional space infrared range with the groundbased capabilities.
The key science objectives emphasize fundamental issues connected to the formation and evolution of galaxies and stars and stellar systems. However, Herschel will be an observatory facility and its unique capabilities will be available to the entire astronomical community for a wide range of observations. Herschel is equipped with a passively cooled 3.5 m diameter classical Cassegrain telescope. The science payload complement – two cameras/medium resolution spectrometers (PACS and SPIRE) and a very high resolution heterodyne spectrometer (HIFI) – is housed in a superfluid helium cryostat. The ground segment is jointly developed by the ESA, the three instrument consortia, and NASA/IPAC. Herschel is scheduled to be launched into a transfer trajectory towards its operational orbit around the Earth-Sun L2 point by an Ariane 5 ECA (shared with the ESA cosmic background mapping mission Planck) in 2009. Once operational about half a year after launch, Herschel will offer 3 years of routine science operations. Almost 20 000 hours of observing time will nominally be made available for astronomy, 32% is guaranteed time, the remainder is open time which is offered to the worldwide general astronomical community through a standard competitive proposal procedure.

The evolution of stars in the mass range 7–12 M๏ is characterized bythe off-center ignition of carbon in condition of partially degeneracyfollowed by the propagation of a convectively bound flame and the formationof a neon-oxygen core. In this chapter, we review the evolutionaryfeatures of these peculiar stars and pay a special attention to thethermally pulsing super-AGB phase and associated nucleosynthesis. Theevolution toward electron capture supernovae for the most massive membersof this class is briefly mentioned. In light of new computations, we alsodiscuss the question of Mup, the critical mass above which carbon ignitesas well as Mn, the minimum mass for the formation of a neutron star andanalyze the dependence of these transition masses on metallicity.

A large fraction of the energy released during solar flares is carried by accelerated electrons and ions. At present the most direct diagnostics of accelerated electrons are the radio emission produced from the microwave to the sub-millimeter domains by gyrosynchrotron emission and the hard X-ray/gamma-ray continuum from electron bremsstrahlung. These diagnostics have brought valuable information on the electron energetics, but the characteristics of relativistic electrons are still poorly known, although they provide the most stringent constraints for acceleration models. This is, at least partly, because radio diagnostics were usually obtained below 100 GHz and gamma-ray measurements were restricted to energies below 100 MeV. Recent radio observations in the 200–400 GHz range have revealed a new spectral component, the origin of which is not yet understood. Observations at higher frequencies are necessary in order to discriminate between different possibilities. Although solar observations in the far infrared domain have not yet been performed, this spectral region contains key information on both relativistic electrons and the response of the low atmosphere to energy deposition from the flare. The combination of observations obtained in the far infrared continuum (2–10 THz) with measurements of high energy gamma-rays (up to 500–600 MeV) will not suffer from the limitations of the present diagnostics and thus provide new constraints on acceleration and energy transport processes.

Some general features of indirect approaches for determining cross sectionsof astrophysically relevant reactions at low energies are discussed from a theoretical point of view. The methodsof Coulomb dissocation (CD), of the asymptotic normalization coefficient(ANC) and the Trojan-horse method (THM) are considered.

Dome Fuji is potentially one of the best astronomical sites in Antarctic plateau. We have a plan to build a 2-m class infrared telescope at Dome Fuji, and have been evaluating the site since the 2006/2007 Antarctic summer. We present the outline of a 2-m class telescope project and some results of our SODAR measurements.

Some recent observations of Classical Cepheids, RR Lyrae and Mira variables are used to illustrate their continued importance as standard candles. Gaia will provide a calibration of these stars as distance indicators which should lead to a greatly improved understanding of the formation and evolution of our Galaxy as well as a vital calibration of the extra-galactic distance scale. The importance of infrared observations, as well as a deeper understanding of interstellar reddening and photometric systems, will play a part if the Gaia calibration is to be put to good use.

The operation of any base or expedition to Antarctica is regulatedby the mutual agreement among nations in the “Antarctic Treaty”.This treaty deals with the major aspects of life in Antarctica andits main principles and provisions are described in what follows.

We have found low-mass star-forming regions with extremely high abundances of carbon-chain molecules. Those are L1527 in Taurus and IRAS 15398-3359 in Lupus. In these sources, carbon-chain molecules would be regenerated in a lukewarm region near the protostar, triggered by the evaporation of the CH4 ice. This is new carbon-chain chemistry (Warm Carbon-Chain Chemistry: WCCC) in contrast to the conventional one applied to cold starless cores. Our interferometric observation shows a steep abundance increase of the carbon-chain molecules inward of a radius of 500 − 1000 AU from the protostar. This size corresponds to the temperature range of 20–30 K, which is close to the evaporation temperature of CH4 (25 K). This result is therefore consistent with the WCCC. The discovery of the WCCC sources demonstrates chemical diversity of low-mass star-forming regions. In particular, a remarkable contrast can be seen between the WCCC and the hot corino chemistry known in IRAS 16293-2422. A possible origin for the diversity would be the time scale of the starless-core phase; a shorter contraction time would result in the WCCC. Relatively low deuterium fractionation ratios in L1527 also support this scenario. If so, chemical compositions will tell us an important clue to understand the source-to-source variation of star-formation processes.

We present a summary of the extensive problems posed by the curious abundance correlations seen in stars in Galactic globular clusters.We discuss three scenarios, and conclude that only one seems to beconsistent with the observations. Even this is still rather unsatisfyingfrom many viewpoints. We determine the kind of nucleosynthesis requiredand discuss AGB stars as the possible source. Some calculations seem torule out AGB stars and others seem to favour them. The reasons for the differences are discussed. No satisfying conclusion is reached!

In this paper, we describe two fully Bayesian algorithms that have been previously proposed to unmix hyperspectral images. These algorithms relies on the widely admitted linear mixing model, i.e. each pixel of the hyperspectral image is decomposed as a linear combination of pure endmember spectra. First, the unmixing problem is addressed in a supervised framework, i.e., when the endmembers are perfectly known, or previously identified by an endmember extraction algorithm. In such scenario, the unmixing problem consists of estimating the mixing coefficients under positivity and additivity constraints. Then the previous algorithm is extended to handle the unsupervised unmixing problem, i.e., to estimate the endmembers and the mixing coefficients jointly. This blind source separation problem is solved in a lower-dimensional space, which effectively reduces the number of degrees of freedom of the unknown parameters. For both scenarios, appropriate distributions are assigned to the unknown parameters, that are estimated from their posterior distribution. Markov chain Monte Carlo (MCMC) algorithms are then developed to approximate the Bayesian estimators.

As of today over 40 planetary systems have been discovered in binary star systems. In all cases the configuration appears to be circumstellar, where the planets orbit around one of the stars, the secondary acting as a perturber. The formation of planets in binary star systems is more difficult than around single stars due to the gravitational action of the companion on the dynamics of the protoplanetary disk. In this contribution we first briefly present the relevant observational evidence for planets in binary systems. Then the dynamical influence that a secondary companion has on a circumstellar disk will be analyzed through fully hydrodynamical simulations. We demonstrate that the disk becomes eccentric and shows a coherent precession around the primary star. Finally, fully hydrodynamical simulations of evolving protoplanets embedded in disks in binary star systems are presented. We investigate how the orbital evolution of protoplanetary embryos and their mass growth from cores to massive planets might be affected in this very dynamical environment. We consider, in particular, the planet orbiting the primary in the system γ Cephei.

We apply a simple, one-equation, galaxy formation model on top of the halos and subhalos of a high-resolution dark matter cosmological simulation to study how dwarf galaxies acquire their mass and, for better mass resolution, on over 105 halo merger trees, to predict when they form their stars. With the first approach, we show that the large majority of galaxies within group- and cluster-mass halos have acquired the bulk of their stellar mass through gas accretion and not via galaxy mergers. We deduce that most dwarf ellipticals are not built up by galaxy mergers. With the second approach, we constrain the star formation histories of dwarfs by requiring that star formation must occur within halos of a minimum circular velocity set by the evolution of the temperature of the IGM, starting before the epoch of reionization. We qualitatively reproduce the downsizing trend of greater ages at greater masses and predict an upsizing trend of greater ages as one proceeds to masses lower than mcrit. We find that the fraction of galaxies with very young stellar populations (more than half the mass formed within the last 1.5 Gyr) is a function of present-day mass in stars and cold gas, which peaks at 0.5% at mcrit = 106−8 M⊙, corresponding to blue compact dwarfs such as I Zw 18.

Accurate characterization of the errors in the global astrometric solution for Gaia isessential for making optimal use of the catalogue data. We investigate the structure ofthe covariance between the estimated astrometric parameters by studying the properties ofthe astrometric least squares solution. We find that astrometric errors can be separatedin a star and an attitude part, due to the estimation of the star and attitude parametersrespectively. Hence the covariances can be separated in a star, an attitude and a crossterm. This is demonstrated using our scalable simulation tool AGISLab, where thecovariances are estimated statistically using Monte Carlo techniques.

Traces of heavy metal in cool DZ white dwarfs may be attributed to the accretion of circumstellar dust. This dust is thought to originate from the tidal disruption of some rocky material, they provide a unique opportunity to study the composition of extra-solar planetary systems. The determinations of precise atmospheric parameters and abundances require accurate description of the line profiles of the identified features. We present absorption spectra of Na-He and Ca+-He for the conditions prevailing in cool white dwarfs.

There is an ongoing debate in the literature concerning the effects of averaging out inhomogeneities (“backreaction”) in cosmology. In particular, some simple models of structure formation studied in the literature seem to indicate that the backreaction can play a significant role at late times, and it has also been suggested that the standard perturbed FLRW framework is no longer a good approximation during structure formation, when the density contrast becomes nonlinear. In this work we use Zalaletdinov's covariant averaging scheme (macroscopic gravity or MG) to show that as long as the metric of the Universe can be described by the perturbed FLRW form, the corrections due to averaging remain negligibly small. Further, using a fully relativistic and reasonably generic model of pressureless spherical collapse, we show that as long as matter velocities remain small (which is true in our model), the perturbed FLRW form of the metric can be explicitly recovered. Together, these results imply that the backreaction remains small even during nonlinear structure formation, and we confirm this within the toy model with a numerical calculation.