Masses of DA white dwarfs with gravitational redshift determinations
Dec 19, 1994
25 pages
Published in:
- Astrophys.J. 444 (1995) 810
DOI:
Report number:
- STEWARD-1231
View in:
Citations per year
Abstract: (ADS)
We estimate effective temperatures and surface gravities for 35 DA white dwarfs with previously published gravitational redshifts, with known systemic velocities based on a companion cluster membership. The spectroscopically determined mass estimates are then compared with those inferred from the redshifts, using in both cases the evolutionary models of Wood. We find that when the redshift velocities from Wegner & Reid are excluded from the sample, the gravitational redshift and spectroscopic masses agree well within 1 sigma, suggesting that the theoretical assumptions used in the model spectra are sound. However, when determinations from this last reference are included in the analysis, strong discrepancies arise: for the sample of stars cooler than Teff is approximately 12,000 K, the scatter in the results from the two methods is much larger than for the hotter stars, and the gravitational redshift masses then appear significantly larger than the spectroscopic masses at all temperatures. An analysis of the ZZ Ceti star G117-B15A yields good agreement with the gravitational redshift determination only if the ML2 parameterization of the mixing-length theory of convection is used in the spectroscopic analysis. The spectroscopic masses alone reveal that cool (Teff is less than 12,000 K) DA white dwarfs appear to have larger masses, a result of which has been interpreted in the past as conclusive evidence for helium enrichment due to the occurrence of convective mixing.References(0)
Figures(0)
0 References