The analysis of emission line region of Seyfert 1 galaxy Mrk 817 is presented. We found that emission line region in Mrk 817 is very complex. Moreover, the Narrow Line Region shows complex structure. The spectral line shapes of Mrk 817 indicates at least three kinematically separated regions, one (or more) which emits the broad line component (V

The NLTE Fe I line formation problem in a three-dimensional granulation model of the metal-poor halo star HD 140283 is considered. The self-consistent solutions of the kinetic and radiative transfer equations were obtained with a realistic atomic model Fe I + Fe II. The effects of horizontal radiative transfer are neglected. The near-UV

We present results of our combined X-ray and optical study of NGC 2451, which actually consists of two different stellar clusters situated along the same line-of-sight at distances of 190 and 360 pc, respectively. Based on ROSAT X-ray observations and on our extensive optical CCD BVR-photometry we are able to identify 113 stars down to spectral

We are using the McDonald 2.7m and ESO 1.52m telescopes to obtain spectra of nearby stars at high-resolution, high S/N, and with complete optical coverage. The sample includes all stars in the Hipparcos catalog brighter than MV = 6.5 (˜ K2 V) within a 12770 pc3 sphere centered at the Sun. The survey is 78 % complete. The database will be publicly

We discuss, in terms of particle acceleration, the results from optical observations with ESO's Very Large Telescope aimed at the detection of the optical counterparts of radio hot spots. To select the targets, we adopted criteria based on theoretical expectations and obtained an unprecedented 70% detection rate. Our results strongly suggest that

We present a detailed spectroscopic investigation, spanning four winters, of the asymptotic giant branch (AGB) star IRAS 02091+6333. Zijlstra & Weinberger (cite{ZW}) found a giant wall of dust around this star and modelled this unique phenomenon. However their work suffered from the quality of the optical investigations of the central object. Our