Is the common envelope ejection efficiency a function of the binary parameters?
Version of Record online: 17 NOV 2011
© 2011 The Authors Monthly Notices of the Royal Astronomical Society © 2011 RAS
Monthly Notices of the Royal Astronomical Society
Volume 419, Issue 1, pages 287–303, January 2012
How to Cite
Davis, P. J., Kolb, U. and Knigge, C. (2012), Is the common envelope ejection efficiency a function of the binary parameters?. Monthly Notices of the Royal Astronomical Society, 419: 287–303. doi: 10.1111/j.1365-2966.2011.19690.x
- Issue online: 13 DEC 2011
- Version of Record online: 17 NOV 2011
- Accepted 2011 August 24. Received 2011 June 23
- methods: statistical;
- binaries: close;
- stars: evolution;
- white dwarfs
We reconstruct the common envelope (CE) phase for the current sample of observed white dwarf main-sequence post-common envelope binaries (PCEBs). We apply multiregression analysis in order to investigate whether correlations exist between the CE ejection efficiencies, αCE inferred from the sample, and the binary parameters: white dwarf mass, secondary mass, orbital period at the point the CE commences, or the orbital period immediately after the CE phase. We do this with and without consideration for the internal energy of the progenitor primary giants’ envelope. Our fits should pave the first steps towards an observationally motivated recipe for calculating αCE using the binary parameters at the start of the CE phase, which will be useful for population synthesis calculations or models of compact binary evolution. If we do consider the internal energy of the giants’ envelope, we find a statistically significant correlation between αCE and the white dwarf mass. If we do not, a correlation is found between αCE and the orbital period at the point the CE phase commences. Furthermore, if the internal energy of the progenitor primary envelope is taken into account, then the CE ejection efficiencies are within the canonical range 0 < αCE≤ 1, although PCEBs with brown dwarf secondaries still require .