%0 Generic
%A Maintz, Monika
%D 2003
%F heidok:4343
%K Be-Stern , spektroskopischer Doppelstern , Be+sdO-Doppelstern , 59 Cygni , phi PerseiBe star , spectroscopic binary , Be+sdO binary , 59 Cygni , phi Persei
%R 10.11588/heidok.00004343
%T Be binary stars with hot, compact companions
%U https://archiv.ub.uni-heidelberg.de/volltextserver/4343/
%X In this study the importance of close binary evolution for Be star formation was investigated. The Be star 59 Cygni was confirmed to be an evolved binary with a sdO companion. The companion was confirmed by a weak helium II absorption. Orbital elements and stellar masses were determined. In the spectrum of 59 Cygni, characteristic features were identified. These are a single-peaked emission component, a phase-locked V/R variability, and a "knotty" structure of the absorption lines. According to Stefl et al. (2000), these features are caused by a hot, compact companion (sdO or WD) that photoionizes a sector of the disc of the Be star. Assuming this model and a code of Hummel and Stefl (2001) the emission variability of 59 Cygni was successfully reproduced. The features, observed in the spectrum of 59 Cygni, were confirmed for the Be+sdO binary phi Persei and for HR2142, too. Hence, these features were taken as indicators for Be binaries with hot, compact companions. HR2142 was confirmed to be a Be+sdO binary. The spectral variability of further candidates was examined. It was suggested that FY CMa is a Be+sdO binary and that kappa Draconis is a Be+WD binary. The assumption that a fraction of the Be stars formed by mass and angular momentum transfer in close binary systems was confirmed.