AAS 203rd Meeting, January 2004
Session 54 White Dwarf Stars
Poster, Tuesday, January 6, 2004, 9:20am-6:30pm, Grand Hall

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[54.05] STIS Spectroscopy of the Hot, Helium-Core White Dwarf in HR 1608

K. M. Sandstrom (U. C. Berkeley), W. B. Landsman (NASA/GSFC/SSAI), G. Torres, D. W. Latham (Harvard-Smithsonian Center for Astrophysics)

The K0 IV star HR 1608 is a single-lined spectroscopic binary with a period of 896 days. IUE spectroscopy of HR 1608 by Landsman et al. (1993) revealed that the companion is a hot white dwarf with a temperature of about 25,000 K. We estimate a white dwarf mass of 0.39±0.02 M\odot by combining the results of our radial velocity monitoring with an astrometric orbit calculated from the Hipparcos Intermediate data and an estimate of the primary mass. Therefore, the white dwarf in HR 1608 must have a helium core.

On 18 Aug 2003 we obtained a STIS medium-resolution echelle (E140M) spectrum of HR 1608 in order to ascertain the presence of spectral lines suitable for determining a UV orbital solution. Such a solution would allow a dynamical estimate of the white dwarf mass which is independent of any assumed mass-radius relation. The STIS spectrum indeed shows narrow lines of N V, Si IV, and C IV at velocities consistent with a photospheric origin. The strength of these high temperature lines is unusual for a DA white dwarf and we discuss possibilities for their origin.

The author(s) of this abstract have provided an email address for comments about the abstract: karin@astron.berkeley.edu

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Bulletin of the American Astronomical Society, 35#5
© 2003. The American Astronomical Soceity.