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UV observations of the cool DBQA5 white dwarf LDS 678A - Limits on the atmospheric composition, pressure shift, and gravitational redshift derived from C I 2479A 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.
Document ID
19910039610
Acquisition Source
Legacy CDMS
Document Type
Reprint (Version printed in journal)
External Source(s)
Authors
Oswalt, Terry D.
(Florida Institute of Technology Melbourne, United States)
Sion, Edward M.
(Villanova University PA, United States)
Hammond, Gordon
(South Florida, University Tampa, FL, United States)
Vauclair, Gerard
(Observatoire Midi-Pyrenees Toulouse, France)
Liebert, James W.
(Steward Observatory Tucson, AZ, United States)
Date Acquired
August 15, 2013
Publication Date
February 1, 1991
Publication Information
Publication: Astronomical Journal
Volume: 101
ISSN: 0004-6256
Subject Category
Astrophysics
Accession Number
91A24233
Funding Number(s)
CONTRACT_GRANT: NSF AST-88-14711
CONTRACT_GRANT: NSF AST-88-02689
CONTRACT_GRANT: NSF AST-88-02687
CONTRACT_GRANT: NAG5-343
Distribution Limits
Public
Copyright
Other

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