A Spectroscopic Determination of the Mass Distribution of DA White Dwarfs

Attention is given to the mass distribution for a sample of 129 DA white dwarfs based on fitting hydrogen line profiles to the predictions of stellar atmosphere models. The atmospheric parameters determined from spectroscopy are shown to be of improved accuracy over those obtained with other techniques. The spectroscopic masses are in good agreement with those inferred from gravitational redshift measurements. The masses obtained for the stars in the Hyades cluster are found to be measurably higher than those obtained from trigonometric parallaxes, although the observed scatter is greatly reduced in the spectroscopic analysis. The observed mass distribution exhibits a narrow peak, but broad and flat tails extend to large and small masses. The mean mass of the distribution is somewhat lower - near 0.56 solar mass - than found in the best previous analyses. The consequences of these results for earlier phases of stellar evolution are discussed.