Common-envelope mergers: A possible channel for forming single sdB stars

Michael Politano, Ronald E. Taam, Marc Van Der Sluys, Bart Willems

Research output: Contribution to journalArticlepeer-review

26 Scopus citations


We quantify an evolutionary channel for single sdB stars based on mergers of binaries containing a red giant star and a lower mass main-sequence or brown dwarf companion in our Galaxy. Population synthesis calculations that follow mergers during the common-envelope phase of evolution of such systems reveal a population of rapidly rotating horizontal branch stars with a distribution of core masses between 0.32 and 0.7 M, that is strongly peaked between 0.47 and 0.54 M,. The high rotation rates in these stars are a natural consequence of the orbital angular momentum deposition during the merger and the subsequent stellar contraction of the merged object from the tip of the red giant branch. We suggest that centrifugally enhanced mass loss facilitated by the rapid rotation of these stars may lead to the formation of single sdB stars for some of these objects.

Original languageEnglish (US)
Pages (from-to)L99-L102
JournalAstrophysical Journal
Issue number2
StatePublished - Nov 10 2008


  • Horizontal-branch-stars
  • Rotation-subdwarfs
  • Stars

ASJC Scopus subject areas

  • Astronomy and Astrophysics
  • Space and Planetary Science


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