Formation of molecular lines in stellar atmospheres.
Abstract
Statistical equilibrium of electronic states of diatomic molecules in stellar atmospheres is examined. Atmospheres discussed are representative of the sun, Arcturus (K-giant) and Betelgeuse (M-supergiant). A comparison of the relative collisional and radiative contributions to the equilibrium of the ground electronic state shows that this state is collisionally controlled and that the line source function for vibration-rotation transitions within this state is equivalent to the Planck function. Examination of the equilibrium for excited electronic states demonstrates that the exchange between these states and the ground electronic state is most probably determined by radiative excitation. This result implies that scattering rather than pure absorption is the appropriate mechanism for the formation of lines belonging to these electronic transitions. The scattering hypothesis is given a preliminary check against solar observations. Areas for future investigations are outlined.
- Publication:
-
Monthly Notices of the Royal Astronomical Society
- Pub Date:
- March 1975
- DOI:
- 10.1093/mnras/170.3.447
- Bibcode:
- 1975MNRAS.170..447H
- Keywords:
-
- Diatomic Molecules;
- Electron States;
- Line Spectra;
- Molecular Spectra;
- Stellar Atmospheres;
- Stellar Spectra;
- Absorption Spectra;
- Electron Transitions;
- Electronic Spectra;
- Giant Stars;
- K Stars;
- M Stars;
- Molecular Rotation;
- Spectrum Analysis;
- Statistical Mechanics;
- Supergiant Stars;
- Astrophysics