Letter to the Editor
Stability and energetics of mass transfer in double white dwarfs
Zhanwen Han 1,2,3 and
Ronald F. Webbink 4
Received 15 July 1999 / Accepted 12 August 1999
The donor star in an interacting double white dwarf lies deep within the potential well of the accretor, a condition which both alters the minimum mass transfer rate needed to generate an Eddington luminosity, and limits the fraction of matter which can be driven from the binary in a super-Eddington wind. That mass loss itself alters the threshold condition for the onset of dynamical instability of the donor star. We show that, unless the mass of the accreting star is extremely near the Chandrasekhar limit, a significant fraction (exceeding 0.5 for accretors of mass ) must be retained, even when the nominal accretion luminosity far exceeds the Eddington limit. In super-Eddington accretion, the accreted envelope almost certainly extends beyond the orbit of the donor, and will trigger white dwarf merger in a common envelope.
Key words: instabilities stars: binaries: close stars: white dwarfs
Send offprint requests to: Z. Han
This article contains no SIMBAD objects.
© European Southern Observatory (ESO) 1999
Online publication: August 25, 1999