Accretion of mass in Algol.

Abstract

Several high resolution IUE spectra of Algol taken in 1978 and 1979 are analysed. Variable additional absorption components for the ultraviolet resonance lines of Mg II, Al III, and Si IV are detected. The additional components show eclipsing effects indicating that they originate in a region near the primary star, Algol A. Moreover, their behaviour is variable with the time of observation. The observations are interpreted in terms of a mass-accretion process, during which high temperature plasma is produced by dissipation of the kinetic energy of the gas falling onto the surface of the primary star. Moreover, the analysed material indicates that a region with high rotational velocity is created near the accreting star. The time-dependence of this region suggests that this takes place during an increase in the mass-transfer rate.