Line blanketing without local thermodynamic equilibrium. I - A hydrostatic stellar atmosphere with hydrogen, helium, and carbon lines
Abstract
A numerical code designed to calculate radiation transport and atmospheric structure under the constraints of statistical equilibrium in atomic transitions and radiative and hydrostatic equilibrium in the medium has been applied to a stellar atmosphere with effective temperature of 35,000 K and surface gravity of 10,000 cm/sq sec. The calculation includes 93 bound-free transitions and 128 bound-bound transitions (112 including radiative rates in 143 multiplet components) between 83 states in 29 ions of nine cosmically abundant species. The calculated depth-dependence of the electron temperature superficially resembles that in local thermodynamic equilibrium (LTE), but the ionization balance shifts toward higher ion states. The transition dominating the thermodynamic equilibrium shifts from C III 977 A in LTE to C IV 1548-1551 A in non-LTE, and the electron temperatures in the upper atmosphere drop by 15 percent. In addition, the ultraviolet continua with energies h-nu greater than 24 eV are from 5 to 100 times stronger in non-LTE. Little change in the hydrogen spectra from previous non-LTE models occurs. The implications for spectral synthesis and ionization in stellar winds are discussed.
- Publication:
-
The Astrophysical Journal
- Pub Date:
- November 1985
- DOI:
- 10.1086/163668
- Bibcode:
- 1985ApJ...298..848A
- Keywords:
-
- Hydrostatics;
- Line Spectra;
- Radiative Transfer;
- Stellar Atmospheres;
- Stellar Spectra;
- Thermodynamic Equilibrium;
- Carbon;
- Computational Astrophysics;
- Electron Transitions;
- Helium;
- Hydrogen;
- Spectral Energy Distribution;
- Ultraviolet Spectra;
- Astrophysics