Hydrogen in a hydrogen-poor white dwarf: Ross 640.
Abstract
Image-tube scans of the DFp white dwarf Ross 640 (EG119) are presented which show a distinguishable H-alpha line, weak H-beta, and possible H-gamma features. Weak features near 5160 and 4300 A are also suggested, but these require confirmation. Model atmospheres and line profiles are most consistent with a temperature of 8500 + or - 300 K and a hydrogen abundance of approximately 0.0003 in a helium-dominated atmosphere. Thus, Ross 640 is the first cool helium-atmosphere degenerate star with a directly determined hydrogen abundance.
- Publication:
-
Astronomy and Astrophysics
- Pub Date:
- August 1977
- Bibcode:
- 1977A&A....60..101L
- Keywords:
-
- Atmospheric Composition;
- H Lines;
- Hydrogen;
- Stellar Atmospheres;
- White Dwarf Stars;
- Line Spectra;
- Spectrum Analysis;
- Stellar Models;
- Stellar Spectra;
- Stellar Temperature;
- Astrophysics