EDP Sciences
Free access
Volume 445, Number 2, January II 2006
Page(s) 647 - 652
Section Stellar structure and evolution
DOI http://dx.doi.org/10.1051/0004-6361:20053288

A&A 445, 647-652 (2006)
DOI: 10.1051/0004-6361:20053288

Numerical stability of mass transfer driven by Roche lobe overflow in close binaries

A. Büning and H. Ritter

Max-Planck-Institut für Astrophysik, Karl-Schwarzschild-Str. 1, 85741 Garching, Germany
    e-mail: hsr@mpa-garching.mpg.de

(Received 22 April 2005 / Accepted 24 August 2005 )

Numerical computation of the time evolution of the mass transfer rate in a close binary can be and, in particular, has been a computational challenge. Using a simple physical model to calculate the mass transfer rate, we show that for a simple explicit iteration scheme the mass transfer rate is numerically unstable unless the time steps are sufficiently small. In general, more sophisticated explicit algorithms do not provide any significant improvement since this instability is a direct result of time discretization. For a typical binary evolution, computation of the mass transfer rate as a smooth function of time limits the maximum tolerable time step and thereby sets the minimum total computational effort required for an evolutionary computation. By methods of "Controlling Chaos" it can be shown that a specific implicit iteration scheme, based on Newton's method, is the most promising solution for the problem.

Key words: binaries: close -- stars: evolution -- stars: mass-loss -- methods: numerical

© ESO 2005