Ultraviolet and optical observations of the mass-losing contact binary SV Centauri

Abstract

SV Cen is a well known early-type contact binary. The less massive component is a slightly evolved B1 star. The secondary is of spectral type B4 III. The period of the system is P = 1.6585 days. SV Cen shows with Ṗ/P = -2 10-5 yr-1 one of the largest known period decreases. We carried out ground-based photoelectric and spectroscopic (coudé) observations at ESO, and high dispersion UV observations at VILSPA, with the aima) to derive new orbital parameters of SV Cenb) to determine further epochs of minima (i.e. to study the period variations)c) to look for possible mass loss indicators in the ultraviolet range.