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T. E. Harrison (NMSU), S. B. Howell (NOAO/WIYN), J. J. Johnson (NMSU)
We have found that the secondary stars in nearly all non-magnetic cataclysmic variables are carbon deficient. This is in contrast to our results on magnetic systems which appear to contain completely normal main sequence secondary stars. We use the stellar atmosphere modeling program ``SPECTRUM'' to generate model atmospheres for these stars to quantitatively measure their carbon abundances. We find that the carbon deficiencies range from about 80% of solar, to < 5% solar. As we have shown recently (Harrison et al. 2005), the secondary stars in magnetic and non-magnetic cataclysmic variables appear to have different evolutionary histories. The secondary stars in non-magnetic systems appear to have begun life with initial masses much greater than is observed today, and what we observe now are the stripped cores of these more massive stars. While the secondary stars in magnetic systems appear to have always been of low mass. Through the use of the atomic and isotopic abundances of CNO species we should be able to place limits on the initial masses of the secondary stars in non-magnetic systems.
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Bulletin of the American Astronomical Society, 37 #4
© 2005. The American Astronomical Soceity.