AAS 200th meeting, Albuquerque, NM, June 2002
Session 75. Novae and Cataclysmics
Display, Thursday, June 6, 2002, 9:20am-4:00pm, SW Exhibit Hall

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[75.10] Simultaneous BVRIJHK Photometry of Cataclysmic Variables: Measuring Orbital Inclination Angles Using Ellipsoidal Variations

H. Osborne, T. E. Harrison (NMSU), S. B. Howell (PSI), J. J. Johnson (NMSU), D. M. Gelino (UCSD)

Until the orbital inclination angle is measured, the masses of the individual components that comprise cataclysmic variables remain highly uncertain. In non-eclipsing systems, the simplest method for measuring the orbital inclination angle is through the detection of the ellipsoidal variations that arise due to the distorted shape of the secondary star. We have begun a program to obtain simultaneous BVRIJHK photometry of CVs to determine their orbital inclination angles. Multi-wavelength data are necessary to help deconvolve the accretion components in these systems. We will present data on several systems, including EF Eri, where we show that the secondary is a brown dwarf with a temperature of 1125 K. The irradiation by the white dwarf primary causes one face of the brown dwarf to be heated to 1600 K. Thus, once every 40 minutes, the spectrum of EF Eri should change from an L-dwarf, to a T-dwarf! Our sparser light curve of LL And also shows the ~ 0.8 mag variations seen in the light curves of EF Eri, suggesting a similar scenario. We find that the orbital inclination angle of SS Aur has been overestimated: we find an inclination angle of 30o, vs. the 45o commonly quoted. The resulting mass for the secondary star in SS Aur is 0.6 Msun, 50% larger than previously estimated. We find no evidence for ellipsoidal variations in CZ Ori, suggesting it has a very low orbital inclination angle.

This research has been partially supported by LANL Subcontract 29676-001-01 37.

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Bulletin of the American Astronomical Society, 34
© 2002. The American Astronomical Soceity.