Search Publications
A Statistical Study of the si IV Resonance Line Parameters in 19 Be Stars
Antoniou, A.; Stathopoulos, D.; Danezis, E. +2 more
Using the GR model, we analyze the ultraviolet Si IV resonance lines in the spectra of 19 Be stars of different spectral subtypes, in order to detect the presence of absorption components and to analyze their characteristics. From this analysis we can calculate the values of a group of physical parameters, such as the apparent rotational and radia…
Studying the UV mg II Resonance Lines in 20 Be Stars
Antoniou, A.; Stathopoulos, D.; Danezis, E. +1 more
Using the GR model, we analyze the UV Mg II resonance lines in the spectra of 20 Be stars of different spectral subtypes, in order to detect the presence of satellite or discrete absorption components. The values of some physical parameters -- rotational, radial and random velocities, as well as the FWHM and the absorbed energy, as a function of t…
Optical Emission Lines and the X-ray Properties of Type 1 Seyfert Galaxies
Popović, L. Č.; La Mura, G.; Ciroi, S. +3 more
In this contribution we report on the study of the optical emission lines and X-ray spectra of a sample of Type 1 AGNs, collected from the SDSS database and observed by the XMM-Newton satellite. Using different instruments onboard XMM, we identify the spectral components of the soft and hard energy bands (in the range from 0.3 keV to 10 keV). The …
Hints on the Broad Line Region Structure of Quasars at High and Low Luminosities
Sulentic, Jack W.; Marziani, Paola; Dultzin, Deborah +2 more
Quasars show a considerable spectroscopic diversity. However, the variety of quasar spectra at low redshifts is non-random: a principal component analysis applied to large samples customarily identifies two main eigenvectors. In this contribution we show that the range of quasar optical spectral properties observed at low-z\ and associated with th…