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Photospheric, circumstellar, and interstellar features of HE, C, N. O, and Si in the HST spectra of four hot white dwarf starsThis paper reports on the observations of four hot white dwarf stars with the spectrographs on the Hubble Space Telescope (HST). The higher resolving power and higher signal/noise, in comparison with IUE, reveals a very rich phenomomenology, including photospheric features from heavy elements, circumstellar features, and the first direct detection of accretion onto the white dwarf component of a binary system. Specific results include the following: Our observations of the ultrahot degenerate H1504+65 confirm that it has a photosphere which is depleted in both H and He, and reveals features of C IV and O VI. The spectrum fits previously published models extremely well. The intermediate-temperature DO star PG 1034+001 has an ultraviolet spectrum showing complex profiles of the well-known resonance doublets of C IV, N v, and Si IV. The O V 1371 line shows a clear separation into a photospheric and a circumstellar component, and it is likely that the same two components can explain the other lines as well. The cooler DA star GD 394 has an extensive system of heavy-element features, but their radial velocity is such that it is highly unlikely that they are formed in the stellar photosphere. Time-resolved spectra of the accreting white dwarf in the V 471 Tau binary system are briefly presented here; they do show the presence of C IV, Si IV, and He II. However, the C IV and He II lines are in emission, rather than in aborption as had been expected.
Document ID
19950061825
Document Type
Reprint (Version printed in journal)
External Source(s)
Authors
Shipman, Harry L. (University of Delaware, Newark, DE United States)
Provencal, Judi (University of Delaware, Newark, DE United States)
Roby, Scott W. (University of Delaware, Newark, DE United States)
Barstow, Martin (University of Leicester Leicester, United Kingdom)
Bond, Howard (Space Telescope Science Institute, Baltimore, MD United States)
Bruhweiler, Fred (Catholic University of America, Washington, DC, United States)
Finley, David (University of California and Eureka Scientific, Berkeley, CA United States)
Fontaine, Gilles (Universite de Montreal Montreal, Canada)
Holberg, Jay (University of Arizona, Tucson, AZ United States)
Nousek, John (Pennsylvania State University University Park, PA, United States)
Date Acquired
August 16, 2013
Publication Date
March 1, 1995
Publication Information
Publication: Astronomical Journal
Volume: 109
Issue: 3
ISSN: 0004-6256
Subject Category
ASTRONOMY
Distribution Limits
Public
Copyright
Other