Active hot stars are hot stars (Teff ≥ 8000 K) exhibiting emission lines (namely hydrogen lines) and IR excess which both originate in a circumstellar environment. In this paper we present in details the SIMECA (SImulation pour Etoiles Chaudes Actives) code which is the only code freely available to model the gaseous environment of active hot stars. It computes line profiles, Spectral Energy Distributions (SED) and intensity maps, which can be directly compared to high angular resolution observations.

Radio synchrotron emission, its polarization and its Faraday rotation are powerful tools to study the strength and structure of interstellar magnetic fields. Total fields in gas-rich spiral arms and bars of nearby galaxies have strengths of 20–30 μG and are dynamically important. Ordered fields with spiral structure exist in grand-design, flocculent and even irregular galaxies. The strongest ordered fields of 5–10 μG are found in interarm regions, sometimes forming “magnetic spiral arms”. Faraday rotation sometimes reveals large-scale patterns which are signatures of coherent fields generated by dynamos, but in most galaxies the field has a complicated structure. – Magnetic fields with X-shaped patterns are observed in radio halos around edge-on galaxies. The synchrotron scale height allows to measure the mean outflow velocity, which seems to increase with the star-formation rate.

The idea that the radio jets in AGN contain materialin relativistic motion is supported by many lines of observationalevidence, including morphology, brightness temperature estimatedwith interferometers and with intrinsic variations, interstellarscintillations, X-rays, and superluminal motion. These are largelyindependent, and taken together make an irrefutable case for relativisticmotion.


We model the cosmic medium as the mixture of a generalized Chaplygin gas and a pressureless matter component. Within a neo-Newtonian approach we compute the matter power spectrum. The 2dFGRS data are used to discriminate between unified models of the dark sector and different models, for which there is separate dark matter, in addition to that accounted for by the generalized Chaplygin gas. Leaving the corresponding density parameters free, we find that the unified models are strongly disfavored. On the other hand, using unified model priors, the observational data are also well described, in particular for small and large values of the generalized Chaplygin gas parameter α.

Galaxies in dense environments of clusters and groups are objects to ram pressure and hydrodynamical effects of the intra-cluster medium (ICM) that can significantly affect their interstellar content (ISM). We perform numerical simulations of the ram pressure stripping using tree/SPH code GADGET with an adapted method for calculating ISM-ICM interactions. We study the stripping effects of various environments of clusters, with compact or large distributions of the ICM, and the role of the disk tilt angle. Our results indicate that the total amount of the momentum transferred by the encountered ICM to the galaxy’s gas may provide the main features of the stripping. To reproduce our numerical results we propose a fitting formula relating the stripped mass fraction to the encountered ICM column density and the tilt angle. This dependence is superior to that on the peak ram pressure seen in Gunn and Gott criterion.

Spectral analysis is the main tool of astrophysical research.Current instrumental technology offers very sensitive CCD detectorswith enough spectral resolution for many purposes.This introductory text is aimed at graduate students starting a thesisin X-ray astronomy, and at non-specialists who wish to analyseX-ray data themselves. It gives the basic tools and explains the basicissues often implicit in specialised papers. X-ray spectroscopy differs from spectroscopy at longer wavelengths because it is photon based with relatively small numbers ofphotons. As a result the Poisson process is at the core of thestatistical description of X-ray spectra. The classicalmodel-fitting procedure is described and illustrated on a detailedexample. It is applicable to any parametric model and anyinstrumental data. High resolution X-ray spectroscopy, now applicable to many sourcesthanks to sensitive grating instruments, allows to measure individuallines accurately. The diagnostics that it offers are very similarto those offered by mid-resolution optical spectroscopy:line ratios, line broadening, absorption lines.

We present the radial velocity (RV) distribution of Carina dSph, obtained using low-, medium- and high-resolution spectroscopic data collected with FORS2 and GIRAFFE at the VLT. We found that regions where the mean RV is smaller the dispersion is also smaller, and the RV distribution is sharper (i.e. the kurtosis attains larger values). The mean RV, when moving to lower Galactic latitude, decreases by ∼ 5kms−1, attains a well defined minimum outside the galaxy center, and a constant value at larger distances. The RV gradient appears to be in the direction of the Carina proper motion. However, this parameter is affected by large uncertainties to reach a firm conclusion. These findings are probably reminiscent of a substructure with transition properties, already detected in dwarf ellipticals, and call for independent confirmations.

At Dome C most of the seeing is located in the lower atmosphere, below 50 meters height.In this introduction we describe ways in which one might mitigate those ground layer seeingeffects and thus be limited solely by the ~0.25 arcsec seeing of the so-called“free atmosphere”.

We report a preliminary study of the main focal plane instrumentfor the IRAIT telescope, currently being built atINAF-Astronomical Observatory of Teramo. The basic requirementsare those of a remotely-controlled camera aimed to perform 10- and20-μm photometry from Dome-C in the standard bandpasses N andQ. Starting from the site properties and the science goals, themain components of AMICA (Antarctic Mid-Infrared CAmera) aredescribed: a Si:As BIB array detector, sensitive in the range 2–28 μm; a fully reflective optical design; a cryostat modified inorder to work at the extreme environmental conditions of theantarctic plateau; a cryocooler maintaining the operatingtemperature of 4.2 K without external intervention; an automatizedand flexible control electronics.
AMICA is designed to fully exploit the unique mid-infrared observing conditions at Dome-C.

In this paper, some basics concepts in statistical approachesfor detection of signals embedded in noise are brieflyreviewed. Though most material presented in the first part ofthe paper is well documented in the litterature (seereferences), some effort is made to provide a self-containedand concise introduction to the subject. The importance andrelevance of the likelihood ratio is highlighted from aBayesian formulation of the problem; the optimal (in the senseof maximized detection probability for given false alarm rates)Neyman Pearson test and likelihood ratio test are discussed inthe general framework of test performance studies. Therefore,the usefullness of the ROCs (Receiver OperatingCharacteristics) is illustrated on simple examples. When someunknown parameters must be taken into account, extension of theprevious approaches are mentionned, with some emphasis put onthe GLRT (generalized likelihood ratio test). Most resultsintroduced in this tutorial are then applied and discussed inthe framework of the extra-solar planet detection problem. Aobservation model involving Poisson random variables isstudied. A thorough study in performed, and the Gaussianasymptotics are discussed in the case where all parameters ofthe model are assumed. In a more realistic situation where someparameters must be estimated, the GLRT is derived and itsperformances are evaluated by Monte Carlo simulation.

The high Antarctic plateau is considered as the best observing site on Earth in the sub-mm and mm bands. Dome C is one of the most elevated all-year-round station in this continent. Due to its peculiar location, it is also characterized by low wind speeds and very low precipitable water vapor contents.Some experiments have been brought there since 1995 and some ancillary data have been recorded. We report here the actual status of the site quality knowledge in the sub-mm and mm bands.

We have searched for magnetic fields in several early B-type stars:βCephei, Slowly Pulsating B (SPB) and in particular Be stars. We recallthe properties of these stars and highlight the problem of the Be phenomenon. Wediscuss two clues towards understanding this phenomenon in terms of pulsations andmagnetic fields. We summarize results from spectropolarimetric observationsobtained at the Pic du Midi (France) and highlight the results for the Be starω Ori and the β Cep star V2052 Oph.

We study the evolution of the emerging and eruptive Active Region (AR) 10930 for which the coronal magnetic field is reconstructed as a nonlinear force-free field along with vector magnetograms obtained from Hinode/SOT/SP data. We show that the AR evolves quasi-statically during several days through a sequence of equilibria until the time of the eruption. In addition this sequence emphasizes the formation and expansion of a coronal Twisted Flux Rope (TFR) which is related to other observed coronal structures. On the other hand, the pre-eruptive and post-eruptive magnetic configurations show that the pre-eruptive TFR plays a crucial role during the eruption.

COCHISE is a 2.6 meter millimetric telescope, mainly devoted to cosmological observations, located at Concordia. In this paper we report on the installation phases and preliminary operations performed with this instrument. At present, COCHISE is the largest telescope located at Concordia, for that reason it represents a pathfinder for future telescopes.

We briefly outline the plans for scientific activities with the International Robotic Antarctic Infrared Telescope (IRAIT), recently mounted at Dome C. We summarize a few fields where infrared observations with the IRAIT telescope can be effective and we focus on a key project for the Commissioning Phase, namely the determination of the luminosity and of evolutionary parameters for evolved Long-Period Variables (LPVs).

Multi-wavelength studies of M supergiants have revealed atmospheric structures with a large range of spatial and temporal scales. Focusing on Betelgeuse, these scales and their perplexing connections from the photosphere to the interstellar medium are reviewed. Of particular current interest is the dynamic origin of the ubiquitous and relatively dust-free mass loss. Is it multiple plumes of convection driven ejecta, episodic ejection of molecular reservoirs, or a more steady and uniform flow? With powerful new facilities such as the VLT and ALMA we may begin to understand the connections and answer such puzzles, but ultimately detailed studies of a sample of M supergiants will be needed to disentangle the physics from the stars’ personalities.

The Balloon-borne Large Aperture Submillimeter Telescope (BLAST) has recently conducted an extragalactic submillimetric survey of the Chandra Deep Field South region of unprecedented size, depth, and angular resolution in three wavebands centered at 250, 350, and 500 µm. BLAST wavelengths are chosen to study the Cosmic Infrared Background near its peak at 200 µm. We find that most of the CIB at these wavelengths is contributed by galaxies detected at 24 µm by the MIPS instrument on Spitzer, and that the source counts distribution shows a population with strongly evolving density and luminosity. These results anticipate what can be expected from the surveys that will be conducted with the SPIRE instrument on the Herschel space observatory.

The ESA Gaia mission uses two telescopes to create the most ambitious survey of the Galaxy. The angle between them must be known with exquisite precision and accuracy. An interferometer: the Basic Angle Monitoring system measures its variations. High quality data have been retrieved and analysed for more than a year. A summary of the in-orbit performance and some early results are presented.

The large galaxies in the Local Group, as all disk galaxies, havediverse stellar populations. A better understanding of thesedifferences, and a physical understanding of the causes, requires moredetailed study of the older populations. This presents a significantchallenge to GAIA but the scientific returns are also significant.

The signature of activity in general, and of stellar magnetic spots in particular, is present in every measurements, including interferometric ones. Indeed, stellar spots can be found on many stellar surfaces, their size and number varying according to their host's magnetic field and rotational velocity. To correctly determine stellar parameters, it is thus necessary to determine and extract stellar activity's signals. Interferometric observables are disturbed by activity, and this observing technique thus constitutes a good way of probing stellar surface. However, magnetic spots sometimes mimic other phenomenon, like a transiting exoplanet. In that case, the combination of several observing techniques, like photometry and interferometry, is mandatory to extract the planetary signal from the spot's one, and then characterize the exoplanet.