Twin Binaries: Studies of Stability, Mass Transfer, and Coalescence
Persistent URL
Author(s)
Lombardi, James C., Jr. (Jamie)
Holtzman, William
Dooley, Katherine L.
Gearity, Kyle
Kalogera, Vicky
Rasio, Frederic A.
Date Issued
August 20, 2011
Abstract
Motivated by suggestions that binaries with almost equal-mass components (“twins”) play an important role in the formation of double neutron stars and may be rather abundant among binaries, we study the stability of synchronized close and contact binaries with identical components in circular orbits. In particular, we investigate the dependency of the innermost stable circular orbit on the core mass, and we study the coalescence of the binary that occurs at smaller separations. For twin binaries composed of convective main-sequence stars, subgiants, or giants with low-mass cores (Mc 0.15M, where M is the mass of a component), a secular instability is reached during the contact phase, accompanied by a dynamical mass transfer instability at the same or at a slightly smaller orbital separation. Binaries that come inside this instability limit transfer mass gradually from one component to the other and then coalesce quickly as mass is lost through the outer Lagrangian points. For twin giant binaries with moderate to massive cores (Mc 0.15M), we find that stable contact configurations exist at all separations down to the Roche limit, when mass shedding through the outer Lagrangian points triggers a coalescence of the envelopes and leaves the cores orbiting in a central tight binary. In addition to the formation of binary neutron stars, we also discuss the implications of our results for the production of planetary nebulae with double degenerate central binaries.
Journal
The Astrophysical Journal
Department
Physics
Citation
Lombardi, J.C. Jr., Holtzman, W., Dooley, K.L., Gearity, K., Kalogera, V., and Rasio, F.A. (2011). Twin binaries: Studies of stability, mass transfer, and coalescence. The Astrophysical Journal 737(2): 1-16. doi: 10.1088/0004-637X/737/2/49.
Publisher
Institute of Physics
Version of Article
Published article
DOI
10.1088/0004-637X/737/2/49.
ISSN
0004-637X
e1538-4357
Rights
This article has been accepted for publication in Astrophysical Journal ©: 2011 Lombardi, J.C. Jr, Holtzman, W., Dooley, K.L., Gearity, K., Kalogera, V., Rasio, F. Published by Institute of Physics. All rights reserved.
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