2006/10/30 by Vayujeet Gokhale, Xiao Meng Peng, Juhan Frank · 2 citations
Physics and Astronomy · #Angular momentum #Astronomy #Astrophysical Phenomena and Observations #Astrophysics #Binary number #Binary star #Binary system #Classical mechanics #Common envelope #Degenerate energy levels #Gamma-ray bursts and supernovae #Instability #Mass ratio #Mass transfer #Mechanics #Perturbation (astronomy) #Physics #Quantum mechanics #Stars #Stellar, planetary, and galactic studies #White dwarf #astro-ph
paper · pdf · doi:10.1086/510119
published as Astrophys.J.655:1010-1024,2007 · Accepted for publication in ApJ
arxiv created 2006/10/30 · openalex publication_date 2007/01/23 · arxiv updated 2009/12/01 · openalex created_date 2020/11/23 · openalex updated_date 2026/08/05
We describe the evolution of double degenerate binary systems, consisting of components obeying the zero-temperature mass-radius relationship for white dwarf stars, from the onset of mass transfer to one of several possible outcomes, including merger, tidal disruption of the donor, or survival as a semidetached AM CVn system. We use a combination of analytic solutions and numerical integrations of the standard orbit-averaged first-order evolution equations, including direct-impact accretion and the evolution of the components due to mass exchange. We include also the effects of mass loss during supercritical (super-Eddington) mass transfer and the tidal and advective exchanges of angular momentum between the binary components. With the caveat that our formalism does not include an explicit treatment of common-envelope phases, our results suggest that a larger fraction of detached double white dwarfs survive the onset of mass transfer than has been hitherto assumed, even if this mass transfer is initially unstable and rises to super-Eddington levels. In addition, as a consequence of the tidal coupling, systems that come into contact near the mass transfer instability boundary undergo a phase of oscillation cycles in their orbital period (and other system parameters). Unless the donor star has a finite entropy such that the effective mass-radius relationship deviates significantly from that of a zero-temperature white dwarf, we expect our results to be valid. Much of the formalism developed here would also apply to other mass-transferring binaries, and in particular to cataclysmic variables and Algol systems.