Importance of bound-free opacity of OH and CH in solar and stellar atmospheres.
Abstract
Absorption cross-sections for bound-free transitions of OH and CH are estimated and their importance in the atmosphere of the Sun and of other stars is examined. It is shown that OH bound-free opacity is most important just beyond the edge of Mg I at 2514 A, where the need of some unknown source of opacity is most significant in the solar atmosphere. The importance of this source of opacity increases with decreasing effective temperature. However, the spectral type where it starts becoming important and the magnitude of its contribution depend on the value of the oscillator strength of the transition and on the form of the repulsive potential which are poorly known. The bound-free opacity of CH is found to be not insignificant in carbon stars; the amount of its contribution depends on the relative abundance of carbon and on inadequately known values of oscillator strengths of different transitions and forms of the potential curves of the upper states.
- Publication:
-
Monthly Notices of the Royal Astronomical Society
- Pub Date:
- March 1975
- DOI:
- 10.1093/mnras/170.3.559
- Bibcode:
- 1975MNRAS.170..559T
- Keywords:
-
- Hydroxyl Emission;
- Opacity;
- Solar Atmosphere;
- Stellar Radiation;
- Absorption Spectra;
- Free Energy;
- Hydrocarbons;
- Molecular Oscillators;
- Nuclear Potential;
- Astrophysics