Astronomy and Astrophysics – Astronomy
Scientific paper
Feb 1991
adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=1991aj....101..583o&link_type=abstract
Astronomical Journal (ISSN 0004-6256), vol. 101, Feb. 1991, p. 583-586.
Astronomy and Astrophysics
Astronomy
10
Cool Stars, Red Shift, Stellar Atmospheres, Ultraviolet Astronomy, White Dwarf Stars, Absorption Spectra, Gravitational Effects, Iue, Spectral Line Width, Stellar Composition, Stellar Mass
Scientific paper
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.
Hammond Gordon
Koester Detlev
Liebert James W.
Marcum Pamela Marie
Oswalt Terry D.
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