Search for metal lines in the spectra of DA white dwarfs. Semiannual Report, 1 October 1984-31 March 1985

Technical Report · Sun Jun 01 04:00:00 EDT 1986

OSTI ID:5429400

Wegner, G A

A theoretical analysis was carried out in order to interpret the ultraviolet spectra of DB white dwarfs obtained earlier with the International Ultraviolet Explorer (IUE) satellite. Here the results of the IUE ultraviolet spectroscopy combined with visual data and model atmospheres of DB white dwarfs are reported. In particular, a search for spectra lines due to the element carbon using the ultraviolet was made. In no case is there a positive detection of carbon and from these data, and upper limits for carbon by number relative to helium are derived in the range of C: He 10 to the minus 5 power to 10 to the minus 7 power for the 16 DB stars with ultraviolet spectra in the temperature range 11400 K T/sub EFF/ less than 2300 K. The low carbon abundances found in the atmospheres of the DB stars agree well with the hypothesis that the atmospheric carbon observed in the cooler DQ members of the helium-rich white dwarf sequence is produced by a convective dredging mechanism.

• Research Organization: Dartmouth Coll., Hanover, NH (USA)
• OSTI ID: 5429400
• Report Number(s): N-86-26263; NASA-CR-176825
• Country of Publication: United States
• Language: English

Related Subjects

640102* -- Astrophysics & Cosmology-- Stars & Quasi-Stellar
Radio & X-Ray Sources
71 CLASSICAL AND QUANTUM MECHANICS
GENERAL PHYSICS
ATMOSPHERES
CARBON
CONVECTION
DATA
DWARF STARS
ELEMENTS
ENERGY TRANSFER
FLUIDS
GASES
HEAT TRANSFER
HELIUM
INFORMATION
MASS TRANSFER
MATHEMATICS
NONMETALS
NUMERICAL ANALYSIS
NUMERICAL DATA
RARE GASES
SPECTRA
STARS
STELLAR ATMOSPHERES
THEORETICAL DATA
ULTRAVIOLET SPECTRA
WHITE DWARF STARS