Abundance analyses of three helium-rich sdB stars

作者：Naslim N^*; Jeffery C S; Ahmad A; Behara N; Sahin T

来源：Astrophysics and Space Science, 2010, 329(1-2): 119-125.

DOI：10.1007/s10509-010-0334-x

• Helium-rich subdwarfs
• Atmospheric parameters
• Abundances
• Evolution

As part of an extended study of the surface abundances of extremely helium-rich hot subdwarfs, high-resolution optical ,chelle 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]a parts per thousand a'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.

• 出版日期2010-10