Diatomic Analytic Molecular Partition Functions for Stellar Atmospheres

O. Cardona and M. G. Corona-Galindo

Instituto Nacional de Astrofísica, Óptica y Electrónica, Apdo. Postal 51 y 216, 72000 Puebla, Pue., México. (ocardona@inaoep.mx), (mcorona@inaoep.mx).

Received 2012 December 10. ]]> Accepted 2013 March 19.

RESUMEN

Se formulan funciones de partición aproximadas y sus derivadas para moléculas diatómicas tomando en cuenta el número finito de niveles. Se desarrolla además un procedimiento para obtener expresiones analíticas compactas, sin parámetros libres, necesarias para la evaluación eficiente de algunos coeficientes termodinámicos de la función de partición para moléculas diatómicas de utilidad en el modelado de atmósferas estelares de baja temperatura.

ABSTRACT

Approximate partition functions and their derivatives for diatomic molecules are formulated taking into account the finite number of levels. A procedure is developed to derive compact analytic expressions, without free parameters, necessary for the efficient evaluation of some thermodynamic coefficients from the partition functions for diatomic molecules useful in modeling low temperature stellar atmospheres.

Key Words: equation of state — plasmas — stars: atmospheres.

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