## Spherically symmetric model atmospheres using approximate lambda operators## III. The equations of statistical equilibrium with occupation probabilities
The occupation probability formalism is implemented into the equations of statistical equilibrium. The equations and corresponding expressions for rates are presented in detail. The improved equations are used for the calculation of sample spherically symmetric NLTE model atmospheres. The difference between this formalism and standard cutoff formula is studied for pure hydrogen atmospheres. It is small for main-sequence and sdO stars. However, a larger difference is found for white dwarfs.
## Contents- 1. Introduction
- 2. The equations of statistical equilibrium
- 3. Computational details
- 4. Results and discussion
- 4.1. Hot main sequence stars
- 4.2. O subdwarfs
- 4.3. White dwarfs
- 5. Conclusions
- Acknowledgements
- Appendix A
- References
© European Southern Observatory (ESO) 1997 Online publication: April 20, 1998 |