Stellar Masses, Kinematics, and White Dwarf Composition for Three Close DA+dMe Binaries

Abstract

We determine the mass functions and mass ratios for three close white dwarf plus red dwarf binaries (EUVE J0720[317, 1016[053, and 2013]400). Hubble Space T elescope Goddard High-Resolution Spectrograph spectra of the He II j1640 and C IV j1550 spectral lines trace the white dwarf orbital motion, and Hamilton Spectrograph echelle spectra (Lick Observatory) and lower dispersion spectra trace the red dwarf orbital motion. The data sets allow us to measure orbital periods and velocities, as well as the white dwarf gravitational redshifts. The red dwarf and white dwarf mass estimates obtained from a combination of independent mass measurements for the white dwarf stars and our new orbital elements help constrain probable evolutionary outcomes. We Ðnd that EUVE J0720[317 will probably come into contact within a Hubble time and that the mass transfer will be unstable on a dynamical time. We also conclude that the much lower secondary masses in EUVE J1016[053 and EUVE J2013]400 exclude the possibility of signiÐcant interaction in these systems. We also present new helium and carbon photospheric abundance measurements in the three white dwarfs. The white dwarf atmospheric composition may show the e †ects of accretion of red dwarf mass-loss material onto its surface. Finally, we study the kinematics of the systems, and we also show that the white dwarf in EUVE J1016[053 is part of a quadruple system.

The 0.33 Day DA Plus [CLC]dMe[/CLC] Binary BPM 6502

“…We found the semiamplitudes of the white dwarf and the red dwarf to be 25.0^13.0 km s~1 and 71.6^1.4 km s~1, respectively. The dMe orbit traced by Ha is actually lower than the true center-of-mass orbit (see a discussion in Vennes, Thorstensen, & Polomski 1999), and the corrected red dwarf semiamplitude is 76.8^4.0 km s~1, from which we estimate a mass ratio in the range q \ 0.33^0.18. The mass of the white dwarf was estimated as 0.50^0.05 M _ , and from our measured mass ratio we estimate the mass for the red dwarf M \ 0.16^0.09…”

A Comparative Study of the Atmospheric Composition of the DA White Dwarfs Feige 24 and G191‐B2B

“…Subsequent evolution of isolated white dwarfs and white dwarfs in close binaries follow di †erent paths. Vennes, Thorstensen, & Polomski (1999) observed relatively large concentrations of helium and carbon in three white dwarfs in postÈcommon-envelope binaries. Heavy elements are possibly accreted from the red dwarf companions onto the white dwarfs.…”

The age, life expectancy, and space density of Post Common Envelope Binaries

“…% Radii of the secondary calculated by using the mass-radius relation given by Politano (1996). References: (1) Bruch (1999), (2) Bragaglia et al (1995), (3) Bleach et al (2000), (4) Kawka et al (2002), (5) Marsh & Duck (1996), (6) Maxted et al (1998), (7) Saffer et al (1993), (8) Kepler & Nelan (1993), (9) Kawka et al (2000), (10) Koester et al (1979), (11) Stauffer (1987), (12) Lanning & Pesch (1981), (13) Guinan & Sion (1984), (14) Schmidt et al (1995), (15) Wood & Saffer (1999), (16) Drechsel et al (2001), (17) Orosz et al (1999), (18) Maxted et al (2002), (19) O'Brien et al (2001), (20) Kilkenny et al (1998), (21) Rauch (2000), (22) Vennes et al (1999), (23) …”