The UV O I triplet and H Lyman β pumping in the ζ Aurigae star HR 6902.
Abstract
The radiative transfer code MULTI has been used, in conjunction with a model photosphere and chromosphere for the primary star of the ζ Aur system HR 6902, and a 14-level oxygen atomic model which incorporates up-to-date atomic data, to investigate the rôle of photoexcitation and hydrogen Lyman β pumping in the UV O I resonance triplet at 1302.168, 1304.858 and 1306.029 Å. The energy difference between the 3D level and the 3P2 ground state is very similar to that of Lyman β, the former giving rise to a transition at λ = 1025.77 Å while the latter has a transition at λ = 1025.72 Å. O I resonance line emission may be enhanced via cascades down to the 3Pe level by the 11286.77-Å transition, and to the 3So level by the 8446.47-Å transition, followed by spontaneous transitions down to the 3P ground state. It is found to be impossible to reproduce the observed IUE integrated flux for the triplet without taking into account the effects of H Lyman β pumping. The part played by collisions is found to be minimal.
- Publication:
-
Monthly Notices of the Royal Astronomical Society
- Pub Date:
- November 1996
- DOI:
- 10.1093/mnras/283.1.77
- Bibcode:
- 1996MNRAS.283...77M
- Keywords:
-
- Stellar Atmospheres: Radiative Transfer;
- Stellar Atmospheres: UV Lines;
- Stellar Chromospheres: UV Spectra;
- Eclipsing Binaries: Stellar Atmospheres;
- Eclipsing Binaries: Radiative Transfer;
- radiative transfer -- binaries: eclipsing -- stars: chromospheres -- stars: individual: HR 6902