NOAO >   Observing Info >   Approved Programs >   2003A-0236

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Proposal Information for 2003A-0236


PI: Heather Osborne, New Mexico State University, hosborne@nmsu.edu
Address: Astronomy Department, Box 30001/MSC 4500, Las Cruces, NM 88003, USA

CoI: Tom Harrison, New Mexico State University
CoI: Steve Howell, Planetary Science Institute
CoI: Bernie McNamara, New Mexico State University

Title: Determining CV Secondary Star Masses through Infrared Ellipsoidal Variations

Abstract: It has recently become clear that our understanding of the nature and evolutionary history of cataclysmic variable (CV) stars is incomplete. Using infrared spectroscopy (OSIRIS and the IRTF's SPEX), Harrison et al. (2002) have found that ^\rm 13C is strongly enhanced in some CVs. The normal ^\rm 12C/^\rm 13C ratio is 89, if the CNO cycle is allowed to run to completion the resulting ratio is ^\rm 12C/^\rm 13C=3. We have identified several CVs with this level of enhancement! CNO processed material has either found its way onto the CV secondary stars, or it has been created by them. In addition, we find strong enhancement of s-process elements in many CV secondary stars. How these abundance anomalies can occur remains a mystery. To help solve this problem requires us to measure the masses of \it both components in CV systems, and this requires us to determine orbital inclinations (to be used with optical, phase-resolved radial velocity data). We request four nights with SQIID to measure the infrared ellipsoidal variations of four to six CV secondary stars (mostly of longer orbital period) to allow us to derive their orbital inclinations.


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