A critical analysis of the ultraviolet temperature scale of the helium-dominated DB and DBV white dwarfs
- Delaware Univ., Newark (USA)
The temperatures of the hottest of the DB and of some of the variable DBV white dwarfs have been reanalyzed, using a new helium-rich model atmosphere grid and archival IUE data. The grid covers variations in the effective temperature, surface gravity, and trace hydrogen abundance. Significantly lower temperatures than those found by earlier investigations are found. This has influence on the issue of which mixing-length theory is the best one for treatment of convection in DB white dwarfs. The prototype of the DBV stars, GD 358, is given particular attention in view of the recently reported HE II 1640-A line. The sensitivity of the new results to input physics is analyzed. It is found that uncertainties in Stark broadening parameters, convective efficiency, and equation of state and the assumptions of a fixed gravity (log g = 8) and a negligible abundance of hydrogen can at most give an error in the effective temperature of 400 K for a typical DB star. The uncertainty on the absolute calibration of the IUE cameras and the effect of small interstellar reddening dominate the error analysis. 46 refs.
- OSTI ID:
- 5913439
- Journal Information:
- Astrophysical Journal; (USA), Journal Name: Astrophysical Journal; (USA) Vol. 370; ISSN ASJOA; ISSN 0004-637X
- Country of Publication:
- United States
- Language:
- English
Similar Records
Evolutionary sequence for DA, DB, DC white dwarfs
Related Subjects
Radio & X-Ray Sources
71 CLASSICAL AND QUANTUM MECHANICS
GENERAL PHYSICS
ABUNDANCE
ATMOSPHERES
CHEMICAL COMPOSITION
CONVECTION
DWARF STARS
ELEMENT ABUNDANCE
ELEMENTS
ENERGY TRANSFER
FLUIDS
GASES
GRAVITATION
HEAT TRANSFER
HELIUM
HYDROGEN
MASS TRANSFER
MATHEMATICAL MODELS
NONMETALS
RARE GASES
SPECTRA
STAR MODELS
STARS
STELLAR ATMOSPHERES
TEMPERATURE MEASUREMENT
ULTRAVIOLET SPECTRA
WHITE DWARF STARS