Open AccessAnalytical solution for the evolution of a binary with stable mass transfer from a giant
Author(s) -
Ritter H.
Publication year - 1999
Publication title -
monthly notices of the royal astronomical society
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.058
H-Index - 383
eISSN - 1365-2966
pISSN - 0035-8711
DOI - 10.1046/j.1365-8711.1999.02845.x
Subject(s) - physics , mass transfer , binary number , rappaport , degenerate energy levels , transfer problem , simple (philosophy) , radius , statistical physics , astrophysics , thermodynamics , quantum mechanics , arithmetic , theology , mathematics , epistemology , computer security , international trade , computer science , business , philosophy
We derive a simple analytical solution for the evolution of a close binary with nuclear time‐scale driven mass transfer from a giant. This solution is based on the well‐known fact that the luminosity and the radius of a giant scale to a good approximation as simple power laws of the mass M c of the degenerate helium core. Comparison with results of numerical calculations by Webbink, Rappaport & Savonije show the analytical solution and the power‐law approximation to be quite accurate. The analytical solution presented does also allow (in parametrized form) for non‐conservative mass transfer. Furthermore, it is shown that the near constancy of the mass‐transfer rate over most of the mass‐transfer phase seen in the results by Webbink, Rappaport & Savonije is not a generic feature of this type of evolution but rather a consequence of a particular choice of parameters. The analytical solution also demonstrates that the level of mass transfer is largely set by the core mass of the giant at the onset of mass transfer. Finally, we show that the model is self‐consistent and discuss its applicability to low‐mass X‐ray binaries.