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N. Andronov (Ohio State U.)
Interactions of close binaries can produce a variety of interesting objects, in particular Cataclysmic Variables and merger products. The orbital period of a binary which loses orbital angular momentum becomes shorter. This is a driving mechanism for the evolution of CVs. Such angular momentum loss can also result in mergers of close MS-MS pairs. In contrast to previous studies this work uses modern version of empirical formulae for angular momentum loss by magnetized stellar winds. Two main differences with the previous prescriptions include the saturation of angular momentum loss rate for fast rotators, and the existence of such in low mass, fully convective stars. Changes in the treatment of angular momentum loss rate have dramatic impact on the evolution of CVs. The CV period gap therefore can not be explained by an abrupt change in the loss rate, contrary to the standard model. The impact of the evolutionary state and rapid rotation of the secondary in CVs has been investigated, and the time average mass accretion rate calculated. Mergers of close primordial binaries (with periods lower than 5-6 days) were found to be sufficient to explain the population of Blue Stragglers observed in open clusters. Observational tests are discussed.
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Bulletin of the American Astronomical Society, 36 5
© 2004. The American Astronomical Society.