| タイトル | Photospheric, circumstellar, and interstellar features of HE, C, N. O, and Si in the HST spectra of four hot white dwarf stars |
| 著者（英） | Finley, David; Bruhweiler, Fred; Barstow, Martin; Fontaine, Gilles; Holberg, Jay; Provencal, Judi; Nousek, John; Bond, Howard; Shipman, Harry L.; Roby, Scott W. |
| 著者所属（英） | NASA Headquarters |
| 発行日 | 1995-03-01 |
| 言語 | eng |
| 内容記述 | This 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. |
| NASA分類 | ASTRONOMY |
| レポートNO | 95A93424 |
| 権利 | Copyright |
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