Abundance analyses of three helium-rich sdB stars
Source: Astrophysics and Space Science, Volume 329, Numbers 1-2, October 2010 , pp. 119-125(7)
Abstract:As part of an extended study of the surface abundances of extremely helium-rich hot subdwarfs, high-resolution optical échelle spectra of the three helium-rich subdwarf B stars LB 1766, SB 21 and BPS 22940-0009 are presented. Opacity-sampled line-blanketed model atmospheres have been used to derive atmospheric properties and surface abundances. All three stars are moderately metal-poor compared with the Sun ([Fe/H]≍−0.4). The first two stars are nitrogen-rich He-sdBs, while the third is a carbon-rich He-sdB. The surface composition and locus of single N-rich He-sdBs are currently best explained by the merger of two helium white dwarfs. C-rich He-sdBs require further investigation.
Document Type: Research article
Publication date: 2010-10-01