Subluminous O Stars - Origin and Evolutionary Links
Abstract
Hot subluminous stars can be roughly divided into B- and O-types. Unlike the latter many sdBs are found in close binaries, indicating that binary evolution plays a vital role. Recent NLTE spectral analyses revealed that an evolutionary link between sdB stars and sdO stars is plausible only for the helium-deficient sdO stars, i.e. they are the likely successors to sdB stars. The atmospheric properties of helium-enriched sdO stars can be explained by the late hot flasher as well as by the white-dwarf merger scenarios, although both models do not match the observed properties of helium-enriched sdO stars in detail. The white dwarf merger scenario is favoured because it naturally explains the scarcity of close binaries amongst helium-enriched sdO stars. A hyper-velocity sdO star moving so fast that it is unbound to the Galaxy has probably been ejected by the super-massive black hole in the Galactic centre.
Cite
@article{arxiv.0804.1527,
title = {Subluminous O Stars - Origin and Evolutionary Links},
author = {Uli Heber},
journal= {arXiv preprint arXiv:0804.1527},
year = {2008}
}
Comments
to appear in "Hydrogen deficient stars", K. Werner & T. Rauch (eds.), ASP Conference Series, Vol. 391, p.245 (2008)