UV observations of the cool DBQA5 white dwarf LDS 678A - Limits on the atmospheric composition, pressure shift, and gravitational redshift derived from C I 2479

Journal Article · Fri Feb 01 00:00:00 EST 1991 · Astronomical Journal; (USA)

DOI:https://doi.org/10.1086/115707· OSTI ID:5867954

Oswalt, T D; Sion, E M; Hammond, G; Vauclair, G; Liebert, J W ^[1]

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1. Florida Institute of Technology, Melbourne (USA) Villanova Univ., PA (USA) South Florida Univ., Tampa (USA) Observatoire Midi-Pyrenees, Toulouse (France) Steward Observatory, Tucson, AZ (USA)

A high-resolution ultraviolet spectrum of the helium-rich degenerate LDS 678A, obtained with the International Ultraviolet Explorer (IUE) satellite, is presented. LDS 678A is the coolest metallic line degenerate (DQ or DZ) yet observed with the IUE echelle. These observations provide a detailed line profile of the strong C I 2479 absorption line and equivalent width W2479 = 2.35 + or - 0.06 A from which theoretical profile fits yield a carbon abundance of log C/He = (-6.7 + or- 0.2). The presence of carbon in a He-rich atmosphere lends credence to the notion that LDS 678A is a transitional case between the DB white dwarfs with nearly pure helium atmospheres and the helium-rich DQ white dwarfs which exhibit carbon bands. Corrected for an inferred pressure shift Vp = + 38 + or - 4 km/s for the C I 2479 line, a gravitational redshift of Vrs = + 26 + or - 13 km/s is deduced from which a most probable mass of 0.55 solar mass is derived. 27 refs.

• OSTI ID: 5867954
• Journal Information: Astronomical Journal; (USA), Vol. 101; ISSN 0004-6256
• Country of Publication: United States
• Language: English

Related Subjects

71 CLASSICAL AND QUANTUM MECHANICS
GENERAL PHYSICS
WHITE DWARF STARS
ULTRAVIOLET SPECTRA
ABSORPTION SPECTRA
ASTRONOMY
CARBON
CHEMICAL COMPOSITION
ELEMENT ABUNDANCE
GRAVITATION
HELIUM
LINE WIDTHS
MASS
RED SHIFT
STELLAR ATMOSPHERES
ABUNDANCE
ATMOSPHERES
DWARF STARS
ELEMENTS
FLUIDS
GASES
NONMETALS
RARE GASES
SPECTRA
STARS
640102* - Astrophysics & Cosmology- Stars & Quasi-Stellar
Radio & X-Ray Sources