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Iue observations of a hot dao white dwarf: implications for diffusion theory and photospheric stratification
| Content Provider | NASA Technical Reports Server (NTRS) |
|---|---|
| Author | Holberg, J. B. Liebert, J. Vauclair, Gerard Sion, E. M. |
| Copyright Year | 1988 |
| Description | Observations of the DAO white dwarf PG1210+533, including the first high dispersion spectrum of a hybrid H-He object of this nature were obtained by IUE. In contrast with hot DAs in the 50,000 K temperature range, PG1210+533 shows no narrow interstellar-like metal lines, in spite of an optically observed He/H abundance of 0.1. This lack of metal makes accretion from the ISM an unlikely source for the He in the PG1210+533 photosphere. A significant discovery in the high dispersion spectrum is the existence of a sharp, non-LTE like, core seen in the He II 1640 line. Such features are detected in DO white dwarfs. A small aperture SWP low dispersion observation reveals the Lyman alpha profile of PG1210+533 to be surprisingly weak and narrow. Fits of this profile using pure H models yielded a T(eff) = 56,000 K. Fits of the Balmer H gamma profile however, yield T(eff) = 42,300 K and log g = 8.5 + or - 0.5 for the same models. It is unlikely that homogeneously mixed H-He atmospheres can resolve the inconsistency between the Lyman alpha and H gamma features in this star. Stratified models involving thin H photospheres may be necessary to explain these results. |
| File Size | 222017 |
| Page Count | 3 |
| File Format | |
| Alternate Webpage(s) | http://archive.org/details/NASA_NTRS_Archive_19890001362 |
| Archival Resource Key | ark:/13960/t1sf7nx66 |
| Language | English |
| Publisher Date | 1988-06-01 |
| Access Restriction | Open |
| Subject Keyword | Astronomy Photosphere Stellar Atmospheres White Dwarf Stars Lyman Alpha Radiation Stellar Temperature Spaceborne Astronomy Atmospheric Stratification Ultraviolet Spectra Iue H Alpha Line Diffusion Theory Ultraviolet Astronomy Ntrs Nasa Technical Reports Server (ntrs) Nasa Technical Reports Server Aerodynamics Aircraft Aerospace Engineering Aerospace Aeronautic Space Science |
| Content Type | Text |
| Resource Type | Article |
