AAS 205th Meeting, 9-13 January 2005
Session 19 Cataclysmic Variable Stars
Poster, Monday, January 10, 2005, 9:20am-6:30pm, Exhibit Hall

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[19.11] The Dependence of the Common Envelope Efficiency on Binary Star System Parameters

K. Weiler, M. Politano (Marquette U.)

Cataclysmic variables (CVs) are a class of interacting binary star systems. A CV consists of a white dwarf that is accreting material from a low-mass, main-sequence donor star. In the formation of CVs, a phase of evolution known as the "common envelope" phase occurs during which a significant amount of mass and angular momentum is shed from the binary. This is accomplished by transferring energy from the orbit into an envelope which is common to both stars. The efficiency of this transfer is parameterized by a quantity known as alpha. Population synthesis studies of CVs have assumed thus far a constant alpha, independent of quantities such as the masses of the stars, and their state of evolution. In this study, we examined a relationship between alpha and the secondary mass. A Monte Carlo population synthesis code was used to generate a theoretical population of Galactic CVs that are forming at the present epoch. This is the first study to examine any dependence of alpha upon binary parameters.

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