AAS Meeting #193 - Austin, Texas, January 1999
Session 44. Modeling Stellar Characteristics
Display, Thursday, January 7, 1999, 9:20am-6:30pm, Exhibits Hall 1

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[44.01] Massive multi-species, multi-level, non-LTE modeling of stellar atmospheres

C. I. Short, P. H. Hauschildt (University of Georgia)

We have incorporated into the {\sc phoenix} model atmosphere code the ability to treat Fe, Ni, and Co up to ionization stage {\sc vi}, Mg, Ca, and Al up to ionization stage {\sc iii}, and S and Si up to ionization stage {\sc iv}, out of local thermodynamic equilibrium (LTE) using a multi-level direct method with large model atoms (\approx 400 levels and \approx 7500 transitions in the case of Ni\,{\sc iii}). These species are critically important for modeling the time development of Novae spectra. We have also added the ability to similarly treat Cs, Rb, and K, which are important for fitting chromospheric models to M dwarf spectra, and Ba which is important for modeling SNe supernovae. This is an increase from 40 to 85 in the total number of ionization stages among all species treated in non-LTE by {\sc phoenix}, and provides an unprecedented ability to directly compute multi-species, multi-level non-LTE solutions with a model atmosphere code. The equation of state, and the chemical, thermal, and hydrostatic equilibrium equations are all solved consistently with the non-LTE equilibrium of the species treated in non-LTE. Also, the addition of many new non-LTE species allows us to compute synthetic spectra with self-consistent, massive non-LTE line blanketing due to many atoms and ions.

The author(s) of this abstract have provided an email address for comments about the abstract: cis@calvin.physast.uga.edu

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