TY - JOUR
T1 - Photospheric, circumstellar, and interstellar features of HE, C, N. O, and Si in the HST spectra of four hot white dwarf stars
AU - Shipman, Harry L.
AU - Provencal, Judi
AU - Roby, Scott W.
AU - Barstow, Martin
AU - Bond, Howard
AU - Bruhweiler, Fred
AU - Finley, David
AU - Fontaine, Gilles
AU - Holberg, Jay
AU - Nousek, John
AU - Sion, Ed
AU - Tweedy, Richard
AU - Wesemael, F.
AU - Vauclair, Gerard
N1 - Copyright:
Copyright 2018 Elsevier B.V., All rights reserved.
PY - 1995/3
Y1 - 1995/3
N2 - This paper reports on the observations of four hot white dwarf stars with the spectrographs on the Hubble Space Telescope. The higher resolving power and higher signal/noise, in comparison with IUE, reveals a very rich phenomenology, 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 absorption as had been expected.
AB - This paper reports on the observations of four hot white dwarf stars with the spectrographs on the Hubble Space Telescope. The higher resolving power and higher signal/noise, in comparison with IUE, reveals a very rich phenomenology, 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 absorption as had been expected.
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U2 - 10.1086/117355
DO - 10.1086/117355
M3 - Article
AN - SCOPUS:0039026179
SN - 0004-6256
VL - 109
SP - 1220
EP - 1230
JO - Astronomical Journal
JF - Astronomical Journal
IS - 3
ER -