Understanding the Spectrum of the Very Hot DA White Dwarf PG 0948+534

摘要

PG 0948+534 is currently one of the hottest DA white dwarf stars, and is also one of the most mysterious. Attempts to model the sharp, deep absorption features of this star have been unsuccessful. In these proceedings we describe our analysis of PG 0948+534. We perform a line survey of the UV spectrum of PG 0948+534, making detections of 300+ absorption features, and identifying four distinct velocity regimes. We find evidence of cireumstellar absorption in the profiles of C ?v and Si ?v. Using nonlocal thermodynamic equilibrium model atmospheres, we are able to correctly model the absorption features of the star, providing abundance measurements for C, N, O, and Si for PG 0948+534 for the first time. We also revise the effective temperature and gravity for this star using models including these new abundances.