We present an analysis of Chandra High Energy Transmission Grating (HETG) spectra of the corona of the critical intermediate-activity, quadruple stellar system ξ UMa. Using the maximum A/B subsystem separation in 2001, we attempted to resolve for the first time in X-rays the two components using the HETG Medium Energy Grating (MEG). We found the Aa

Frequency differences between high-order p-modes of two stellar models, both with the mass and luminosity of the sun, are compared with results of asymptotic theory. The computed relative differences are closely approximated by averages of the relative sound-speed differences, weighted by the local sound travel-time, over the regions where the

We analyze the stellar distribution in the Galactic disc via NIR color-magnitude diagrams (CMDs). Extinction measurements in the K band are also extracted from the diagrams both for supporting stellar counts predictions of the Besançon and "SKY" models and for comparing with a three dimensional model of the Galactic extinction. The method is based

The old stellar populations of the Milky Way carry the signature of their formation environment and dynamical history in their kinematics and chemical abundances. In particular, the dynamically hot thick disk and halo contain the oldest stars in the Galaxy, and are remnants of its more chaotic past. We present a study of the high-latitude thick

We present spatially resolved kinematics and global stellar populations and mass-to-light ratios for a sample of 39 dwarf early-type (dE) galaxies in the Virgo cluster studied as part of the SMAKCED stellar absorption-line spectroscopy and imaging survey. This sample is representative of the early-type population in the Virgo cluster in the

Starforming galaxies with compact morphology and high optical luminosity (LBCGs) are very common at redshitfs z = 0.4 - 1.2. Those galaxies are believed to have evolved more than other galaxy class during the last ~ 8 Gyr, and are a mayor contributor to the global star formation rate density of the universe at z ~ 1. A robust way to gauge their