AAS Meeting #194 - Chicago, Illinois, May/June 1999
Session 52. White Dwarfs, Neutron Stars and Pulsars
Display, Tuesday, June 1, 1999, 10:00am-7:00pm, Southeast Exhibit Hall

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[52.03] White Dwarfs in Common Proper Motion Binary Systems: Mass Distribution and Kinematics

N.M. Silvestri, T.D. Oswalt, M.A. Wood (Florida Inst. of Tech.), J.A. Smith (University of Michigan), N. Reid (California Inst. of Tech.), E.M. Sion (Villanova University)

We present the gravitational redshifts, mass distribution, radial velocities, and space motions of 70 white dwarf (WD) stars in common proper motion binary (CPMB) systems. The mass distribution we derive has a mean of 0.634 +/- 0.245 Msun. This distribution has a larger mean and higher dispersion than previous studies. We hypothesize that this is due to a higher fraction of cool (average Teff ~ 10,000 K), old WDs in our sample. The individual WD masses we report here agree most closely with those determined from atmospheric profile fits than with masses determined by previous gravitational redshift studies. We believe this is because measurement bisaes, which may have affected the latter, have been minimized in our study. Alternatively, a higher mean WD mass would be associated with binary membership.

A first list of complete space motions for cool WDs is presented, derived from differential measures between WDs and their nondegenerate companions. We find that the UVW space motions of the CPMB pairs which contain WD components is consistent with those of old, metal poor disk stars.

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