We calculate precise stellar radii and surface gravities from the asteroseismic analysis of over 500 solar-type pulsating stars observed by the Kepler space telescope. These physical stellar properties are compared with those given in the Kepler Input Catalog (KIC), determined from ground-based multi-color photometry. For the stars in our sample

The transit of Venus in 2004 offered the rare possibility to remotely sense a well-known planetary atmosphere using ground-based absorption spectroscopy. Transmission spectra of Venus' atmosphere were obtained in the near infrared using the Vacuum Tower Telescope (VTT) in Tenerife. Since the instrument was designed to measure the very bright

We present Gran-Telescopio-Canarias/OSIRIS optical spectra of four of the most compact and massive early-type galaxies (ETGs) in the Groth Strip Survey at redshift z ~ 1, with effective radii R e = 0.5-2.4 kpc and photometric stellar masses M sstarf = (1.2-4) × 1011 M sun. We find that these galaxies have velocity dispersions σ = 156-236 km s-1

Context. The detection of pulsational frequencies in stellar photometry is required as input for asteroseismological modelling. The second short run (SRa02) of the CoRoT mission has provided photometric data of unprecedented quality and time-coverage for a number of O-type stars. Aims: We analyse the CoRoT data corresponding to three hot O-type

High Mass X-Ray Binary systems (HMXRB) are composed by a compact object orbiting around a OB massive star. The mass transfer which takes place from the massive star onto its compact companion is the responsible of the emission of high energy photons (X-rays) observed in these systems (to which they owe the name of their class). The presence of a

Aims: We study the equilibrium and stability of twisted magnetic flux tubes with mass flows along the field lines. Then, we focus on the stability and oscillatory modes of magnetic tubes with uniform twist B0 = B0(r/p eϕ + ez) in a zero-β plasma, surrounded by a uniform, purely longitudinal field. Methods: First we investigate the possible