Criticism of recent calculations of common envelope ejection

Abstract

We re-examine a recent claim by Han et al. (2002) that the ionization energy in the envelope has to be included in the ejection criterion of common envelopes. In particular, we argue that (1) they include a mass loss rate prior to the onset of the common envelope that is too low; (2) They do not include the energy radiated by the accreting white dwarf companion, as well as that emitted by the core of the giant star; and (3) As argued by one of us before, the opacity in the envelope is too low for the efficient usage of the ionization energy.