Masses and envelope binding energies of primary stars at the onset of a common envelope

Marc Van Der Sluys*, Michael Politano, Ronald E. Taam

*Corresponding author for this work

Research output: Chapter in Book/Report/Conference proceedingConference contribution

3 Scopus citations

Abstract

We present basic properties of primary stars that initiate a common envelope (CE) in a binary, while on the giant branch. We use the population-synthesis code described in Politano et al. [1] and follow the evolution of a population of binary stars up to the point where the primary fills its Roche lobe and initiates a CE. We then collect the properties of each system, in particular the donor mass and the binding energy of the donor's envelope, which are important for the treatment of a CE. We find that for most CEs, the donor mass is sufficiently low to define the core-envelope boundary reasonably well. We compute the envelope-structure parameter λenv from the binding energy and compare its distribution to typical assumptions that are made in population-synthesis codes. We conclude that λenv varies appreciably and that the assumption of a constant value for this parameter results in typical errors of 20-50%. In addition, such an assumption may well result in the implicit assumption of unintended and/or unphysical values for the CE parameter αCE. Finally, we discuss accurate existing analytic fits for the envelope binding energy, which make these oversimplified assumptions for λenv, and the use of λenv in general, unnecessary.

Original languageEnglish (US)
Title of host publicationInternational Conference on Binaries - In Celebration of Ron Webbink's 65th Birthday
Pages13-18
Number of pages6
DOIs
StatePublished - 2010
EventInternational Conference on Binaries: In Celebration of Ron Webbink's 65th Birthday - Mykonos, Greece
Duration: Jun 22 2010Jun 25 2010

Publication series

NameAIP Conference Proceedings
Volume1314
ISSN (Print)0094-243X
ISSN (Electronic)1551-7616

Other

OtherInternational Conference on Binaries: In Celebration of Ron Webbink's 65th Birthday
CountryGreece
CityMykonos
Period6/22/106/25/10

Keywords

  • binaries: close
  • stars: evolution
  • stars: fundamental parameters
  • stars: mass loss

ASJC Scopus subject areas

  • Physics and Astronomy(all)

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    Van Der Sluys, M., Politano, M., & Taam, R. E. (2010). Masses and envelope binding energies of primary stars at the onset of a common envelope. In International Conference on Binaries - In Celebration of Ron Webbink's 65th Birthday (pp. 13-18). (AIP Conference Proceedings; Vol. 1314). https://doi.org/10.1063/1.3536356