The WO Wolf-rayet stars.
Abstract
The intensities of all the recombination lines in the dereddened spectrum of Sand 3 are measured and compared with theoretical recombination line predictions for the relevant ions as calculated by Hummer and Storey (1982). The results for the case where the electron temperature is 200,000 K and the density is 10 to the 11th/cu cm are found to have given an excellent fit to the observed relative line intensities of transitions within He II, C IV, C V, O VI, O VII, and O VIII, covering upper levels as low as 3 and as high as 15 over the wavelength range 1170-7100 A. The derived relative abundances (by number), normalized to He(2+) = 100, are presented. The surface chemical composition of Sand 3 (by mass) is therefore H:He:C:O = 0:38:54:8. Since the mass fraction of oxygen in a ZAMS star is only 1%, these results suggest enhancement of oxygen through a alpha-particle capture by carbon in addition to the expected enhancement of carbon by the triple-alpha process.
- Publication:
-
Wolf-Rayet Stars: Observations, Physics, Evolution
- Pub Date:
- 1982
- Bibcode:
- 1982IAUS...99..387B
- Keywords:
-
- Abundance;
- Radiative Recombination;
- Stellar Spectra;
- Wolf-Rayet Stars;
- Alpha Particles;
- Electron Energy;
- Oxygen;
- Stellar Spectrophotometry;
- Astrophysics