Hydrogen and calcium in DB white dwarfs - a case for interstellar accretion

Journal Article · Fri Jul 01 04:00:00 EDT 1988 · Astrophys. J.; (United States)

DOI:https://doi.org/10.1086/185204· OSTI ID:6766828

Sion, E M; Aannestad, P A; Kenyon, S J

Detections of calcium in two DBA stars and in two DB stars as well as possible detections of calcium and/or hydrogen in three additional DB degenerates, from moderate-resolution spectra obtained at the Multiple Mirror Telescope are reported. Calcium and hydrogen abundances and abundance limits which are close to the cosmic abundance have been derived. This finding would appear to indicate that accretion of interstellar hydrogen and grains can effectively occur in some single helium-rich degenerates up to effective temperatures of at least 20,000 K. If a propeller mechanism is operative in DB stars, the results would suggest that the mechanism may break down or be less efficient in a significant fraction of these objects. 23 references.

• Research Organization: Villanova Univ., PA (USA); Arizona State Univ., Tempe (USA); Harvard-Smithsonian Center for Astrophysics, Cambridge, MA (USA)
• OSTI ID: 6766828
• Journal Information: Astrophys. J.; (United States), Journal Name: Astrophys. J.; (United States) Vol. 330; ISSN ASJOA
• 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
ABUNDANCE
ALKALINE EARTH METALS
CALCIUM
CHEMICAL COMPOSITION
DWARF STARS
ELEMENTS
HYDROGEN
INTERSTELLAR SPACE
MASS TRANSFER
METALS
NONMETALS
SPACE
STAR ACCRETION
STAR EVOLUTION
STARS
WHITE DWARF STARS