White Dwarf Companions of Barium and CH Peculiar Stars
Abstract
In 1980 McClure et al.(ApJ 238, L35) discovered that all Bastars show radial velocity variations indicative of theirbinary nature. These authors already suspected that thecompanions are white dwarfs. White dwarf companions wereindeed detected for the Ba star zeta Cap and the mild Ba starzeta Cyg (Boehm-Vitense 1980, ApJ 239, L79) by means of IUEobservations. Evidence for a high temperature radiation fieldwas seen in the spectra of the mild Ba stars HR1016, 16Ser and56UMa. If present, the white dwarf companions are too faint tobe seen with IUE. We would like to look for them now with HST.It seems to us to be very important to check whether indeedall Ba stars have white dwarf companions. If so this makes ithighly probable that the peculiar abundances are due to masstransfer from a very luminous companion to the present Bastar. After losing its envelope the luminous companion wasleft as the present white dwarf. This opens up the possibilitythat other peculiar abundances seen in other peculiar starslike the CH stars or perhaps also the weak G band stars mightalso be due to mass transfer. On the other hand if the whitedwarfs are not found for all Ba stars we may have to look forother processes, that could bring to the surface of thesestars material which has experienced the slow neutron captureprocess.
- Publication:
-
HST Proposal
- Pub Date:
- July 1996
- Bibcode:
- 1996hst..prop.6594B