Astron. Astrophys. 326, 277-286
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Spherically symmetric model atmospheres
approximate lambda operators
III. The equations of statistical equilibrium with
Astronomický ústav, Akademie vd
eské republiky, 251 65 Ondejov, Czech Republic
Received 7 March 1997 / Accepted 22 April 1997
The occupation probability formalism is implemented into the equations
of statistical equilibrium.
The equations and corresponding expressions for rates are presented in
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.
Key words: stars: atmospheres - atomic processes - methods:
© European Southern Observatory (ESO) 1997
Online publication: September 9, 1997
Last change: April 20, 1998