We perform an analysis of spectra and photometry for 22,770 stars included in the third data release (DR3) of the Sloan Digital Sky Survey (SDSS). We derive atmospheric parameters and distances. Our analysis procedures are throughly checked using three recently published spectroscopic libraries of nearby stars and alternative methods. The SDSS

The galaxy cluster RX J0152.7-1357 at z=0.8325 is one of the most luminous X-ray clusters known. It is elongated toward the bright, nearby, X-ray active galaxy NGC 720 about 14' away. At the same distance on the other side of that galaxy is an X-ray blue stellar object with a flux of 5.8 counts ks-1 in the ROSAT PSPC detector. An intermediate

We present a new method, the coupled escape probability (CEP), for exact calculation of line emission from multi-level systems, solving only algebraic equations for the level populations. The CEP formulation of the classical two-level problem is a set of linear equations, and we uncover an exact analytic expression for the emission from two-level

We present a scientific case approached through high quality 3D NIR spectroscopy performed with CIRPASS, attached to the Gemini South telescope. A binary mass concentration at the nucleus of the galaxy M 83 was suggested by Thatte et al. [A&A 364 (2000) L47] and Mast et al. [BAAA 45 (2002) 98. Astroph#0505264] determined the possible position of

We report the results from an homogeneous analysis of the X-ray (ACIS-S/Chandra) data available for a sample of 52 LINER galaxies. The X-ray morphology has been classified attending to their nuclear compactness in the hard band (4.5-8.0 keV), into 2 categories: AGN-like nuclei (with a clearly identified unresolved nuclear source) and Starburst-like

The development of fast numerical methods for multilevel radiative transfer (RT) applications often leads to important breakthroughs in astrophysics, because they allow the investigation of problems that could not be properly tackled using the methods previously available. Probably, the most familiar example is the so-called Multilevel Accelerated