The Gaia Attitude Model (GAM) is a simulation package that is developed to achieve adetailed understanding of the Gaia spacecraft attitude. It takes into account externalphysical effects and considers internal hardware components controlling the satellite. Themain goal of the Gaia mission is to obtain extremely accurate astrometry, and thisrequires a good knowledge of Gaia’s behaviour as a spinning rigid body under the influenceof various disturbances.

This chapter deals with the very simple situation where the mean of a variable, the response variable, usually denoted Y, is linearly depending on another variable, the regressor, here denoted x1. The least squared method is used to get the parameter estimators and estimates of their precisions. This leads to design confidence and prediction intervals, significance tests, anova table. Residuals, diagnostics to identify influent observations and outliers are presented. Methods to detect departures from the model's assumptions and ways of dealing with these departures are addressed.

Along the chapter a data set is used to illustrate the methods with the sofware R.

21-cm studies of the Galactic extra-planar gas layer can help us understand the origin of the gaseous Galactic halo and its interaction with the Milky Way disk. The 100-m Effelsberg radio telescope was utilized to detect and analyze a population of Hi halo clouds belonging to this layer, at Galactocentric radii R > 8.5kpc, following Galactic rotation. This sample of clouds has similar properties to the population detected by Lockman with the GBT at R < 8.5kpc. High resolution follow-up observations resolve them into a number of small, dense, cold arc-minute sized Hi cores. Their study provides evidence for a thermal equilibrium with the extended warmer envelopes. Single dish observations with the 300-m Arecibo telescope disclosed a sample of Hi clouds with similar properties. A power spectrum analysis of the Arecibo maps probes the characteristics of turbulence as a dominant physical process in the halo region.

Interferometry in the visible now provides milliarcsecond spatial resolution and thus has been intensely used for studying the circumstellar environment of evolved and pre-sequence stars. Up to now, most of the scientific results were obtained using only the modulus of the visibility as a function of baseline, time or projected baseline (the so-called "super-synthesis" effect). In this paper we will try to show that even without images, the phase of the visibility is able to put very strong constraints on stellar modeling since it is possible to achieve μarsecond measurements using this technique. We will illustrate through two examples from the GI2T interferometer how the modulus and the phase of the visibility were used to understand the physics of Be disks. We will stress on the importance and the potential of coupling high angular resolution with high spectral resolution for the study of stellar physics. Finally, We will present a possible study on the phase signatures due to stellar rapid rotation that can be done using the VLTI interferometer.

Most of the mass of the interstellar medium is in neutral phases that are heated by far-ultraviolet radiation from star forming regions. The gas, in turn, emits line radiation in the infrared and submillimeter that potentially has great diagnostic value. In this paper, we will review the physical processes (including heating, cooling, gas phase and grain surface chemistry) that give rise to this line emission and present diagnostic diagrams. We will also discuss several examples where models of neutral gas emission have been used to interpret line emission, including observations of H2O and O2 in molecular clouds and an example which points out the caution that must be used when applying the diagnostics to kiloparsec-sized regions in other galaxies.

This report provides the recommendations of ARENA Working Group 1 concerning the development of and objectives for a wide-field, optical/infrared, 2.5 m class telescope for Antarctica. It discusses the key science drivers for such a telescope, the performance and capabilities it should have, and the logistics and infrastructure issues relevant to its construction and operation.

We present a preliminary data release from our multi-year campaign at Keck Observatory tostudy the host galaxies of a large sample of Swift-era gamma-ray bursts via multi-colorground-based optical imaging and spectroscopy. With over 160 targets observed to date (andalmost 100 host detections, most of which have not previously been reported in theliterature) our effort represents the broadest GRB host survey to date. While targetingwas heterogeneous, our observations span the known diversity of GRBs including shortbursts, long bursts, spectrally soft GRBs (XRFs), ultra-energetic GRBs, X-ray faint GRBs,dark GRBs, SN-GRBs, and other sub-classes. We also present a preview of our database(currently available online via a convenient web interface) including a catalog ofmulti-color photometry, redshifts and line ID’s. Final photometry and reduced imaging andspectra will be available in the near future.

One of the most fundamental discoveries in physics and astrophysicswas made with the discovery of pulsars. Ever since, pulsars – andlater in particular binary and millisecond pulsars – have beenstudied as extreme end-states of stellar evolution, as super-denseobjects, as radio and high-energy sources, as probes for theinterstellar medium, and as super-precise clocks for fundamentalexperiments in gravitational physics. This article reviews some of theexciting applications of pulsar physics and the amazing prospects thatare promised by the advent of the Square-Kilometre-Array (SKA).

Here we briefly summarize our long period experience of constructing and operatingwide-field monitoring cameras with sub-second temporal resolution to look for opticalcomponents of GRBs, fast-moving satellites and meteors. General requirements for hardwarefor such systems are discussed along with algorithms of real-time detection andclassification of various kinds of short optical transients. We also give a status reporton the next generation, multi-objective and transforming monitoring system, theMegaTORTORA, whose 6-channel (Mini-MegaTORTORA-Spain) and 9-channelprototypes (Mini-MegaTORTORA-Kazan) we are building now at SAO RAS. This system combines awide field of view with subsecond temporal resolution in monitoring regime, and is able toreconfigure itself, in a fractions of second, to follow-up mode which has bettersensitivity and provides us with multi-color and polarimetric information on detectedtransients simultaneously.

Elliptical galaxies follow a well-known luminosity – metallicity (L − Z) relation, in the sense that more luminous ellipticals are observed to be more metal-rich than less luminous systems. Obviously this is a mass – Z relation, and its interpretation is that less massive galaxies had more significant outflows of metal-enriched gas at an early evolutionary stage. The apparent ellipticity (ϵ) had already been invoked to explain the large scatter in the L − Z relation, but Barazza & Binggeli (2002) observed that the relation between Z and ϵ in cluster dwarf elliptical galaxies (dEs) could even be stronger than the relation with mass. The idea is that outflow of metal-enriched gas preferentially occurs along the minor axis, making ϵ a critical parameter for Z in dwarfs. Here, we test this hypothesis using high-resolution N-body/SPH simulations including chemical feedback of dEs with different flattenings.

We present a method to measure the dynamical mass of extrasolar planets in multiple stellar systems with a single aperture from the ground using high-precision relative astrometry. To reach the precision needed, accurate monitoring of the astrometric stability (pixel scale, orientation, and field distortions of the detector) is necessary. Thus, we always observe an astrometric calibration cluster to compare these astrometric criteria with those of our observations. For our first target observed, the binary HD 19994, we achieved a relative precision of 100...150 µas which is sufficient to detect an astrometric companion around the A component down to about 5 MJup.

Using a variety of laboratory analogues and some simple models, Itry to portray the fluid dynamics of very hot stars and disks. By analogy to fluidizedbeds, we may expect the formation of photon bubbles that stir things up intoa sort of turbulence. Because of rotation, the bubbles merge tomake vortices whose presence causes inhomogeneous radiative outflowsand produces spots. These phenomena will allow the Eddington limit to be exceeded and, where the radiative outflows are locally large, mass loss will be encouraged.

This chapter describes non supergiant B-type stars that show emission lines, called Be stars. The emission is caused by the presence of a circumstellar decretion disk. Many physical phenomena are thought to be involved in these stars, such as rapid rotation, pulsations and magnetic fields, and give rise to variations. Spectroscopy is used as a diagnostic tool to study Be stars, by professional astronomers as well as by amateurs.

I present observations of shock-processed PAHs and dust in supernova remnants (SNRs).Supernova shocks are one of the primary sites destroying, fragmenting and alteringinterstellar PAHs and dust. Studies of PAHs through supernova shocks had been limitedbecause of confusion with PAHs in background emission. Spitzerobservations with high sensitivity and resolution allow us to separate PAHsassociated with the SNRs and unrelated, Galactic PAHs. In the young SNR N132D, PAHfeatures are detected with a higher PAH ratio of 15–20/7.7 μm than thoseof other astronomical objects, and we suggest large PAHs have survived behind the shock.We present the spectra of additional 14 SNRs observed with Spitzer IRSand MIPS SED covering the range of 5–90 μm. Bright PAH features from 6.2to 15–20 μm are detected from many of SNRs which emit molecular hydrogenlines, indicating that both large and small PAHs survive in low velocity shocks. Weobserve a strong correlation between PAH detection and carbonaceous small grains, while afew SNRs with dominant silicate dust lack PAH features. We characterize PAHs depending onthe shock velocity, preshock density and temperature of hot gas, and discuss PAH and dustprocessing in shocks and implication of PAH and dust cycles in ISM.

We summarize results of magnetic measurements of the bright early B-type stars β Cep, ζ Cas, and V2052 Oph, which we found to be oblique rotators with a weak magnetic dipole field with polar strength of a few hundred Gauss. From stellar wind studies we derived their rotational periods very accurately, and matched the magnetic and stellar wind phases. From model atmosphere fits we derived the angles of the rotation and magnetic axis. All three stars show some chemical abundance anomaly, likely associated with the magnetic properties. The stars are also pulsating variables. This is of high asteroseismological interest, since these are the only early-type stars known with observationally determined rotation, pulsation and magnetic properties.

Convective overshoot is a physical mechanism for which no recipe based on first principles is available; hence the necessity of assuming some parametrisations, which undermine the predictive power of the current generation of stellar models. We evidentiate the non local aspects of the convective phenomenon particularly in the proximities of the convective borders, and identify some cases when the use of a diffusive rather than the classic instantaneous approach to describe overshooting is highly recommended.

The approximation known as Frozen Convection has been widely used in the context of stellar oscillations due to the lack of a Time Dependent Convection theory. This approximation supposes to neglect the interaction between convection and oscillations and there are different ways to do it. The choice can affect theoretical predictions concerning the non-adiabatic treatment of the stellar oscillations. In fact, fictitious excitation or damping of the pulsation modes can be produced depending on the approximation used.

As potential progenitors of the Ap stars, the pre-main sequence intermediate mass Herbig Ae/Be stars present us with the opportunity to investigate theearly history of magnetic fields at these masses. Although we have nodirect evidence for the presence of magnetic fields in thesestars (except in one case), many clues for such fields have been identified in the past years. They include active phenomena which areoften attributed to surface magnetic fields. Rotational modulation ofspectral lines formed at the photosphere and in the wind of these starsconstitutes yet another indication for the presence of such fields. Future prospects for the detection and mapping of hypotheticalmagnetic fields in Herbig Ae/Be stars are very encouraging, andin particular spectropolarimetric observations of these stars withinstruments like Espadons on CFHT will allow us to test thehypothesis that magnetic fields similar to those found on Ap starsare indeed present in these pre-main sequence objects.

I briefly outline a new physical interpretation to the average cosmological parameters for an inhomogeneous universe with backreaction. The variance in local geometry and gravitational energy between ideal isotropic observers in bound structures and isotropic observers at the volume average location in voids plays a crucial role. Fits of a model universe to observational data suggest the possibility of a new concordance cosmology, in which dark energy is revealed as a mis-identification of gravitational energy gradients that become important when voids grow at late epochs.