Be binary stars with hot, compact companions

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.

Level thesis:degree_level

thesis.doctoral

Grantor dc:publisher

Universität Heidelberg

Year

2003

Author dc:creator

• Maintz, Monika

Contributors dc:contributor

• Appenzeller, Immo,

Repository record source_url

http://www.ub.uni-heidelberg.de/archiv/4343

OAI identifier oai:identifier

oai:archiv.ub.uni-heidelberg.de:4343