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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[44.08] The Lyman Continuum of O stars From Hydrostatic Spherical Non-LTE Line-Blanketed Model Atmospheres

J. P. Aufdenberg (Arizona State University), P. H. Hauschildt (University of Georgia), E. Baron (University of Oklahoma)

We have used the parallelized version of the stellar atmosphere and radiative transfer code PHOENIX to compute a set of 45 non-local thermodynamic equilibrium (NLTE) stellar atmosphere models and synthetic spectra corresponding to O stars. These hydrostatic models are computed with spherical geometry treating the ~ 5000 levels of H I, He I-II, C I-IV, N I-VI, O I-VI, Mg II, Ca II, Ne I, S II-III, Si II-III and Fe I-III in NLTE. In addition, approximately 5 million background LTE lines are included in the total line-blanketing. For this set of models, we use a solar metal abundance. We compare the ionizing Lyman continuum fluxes from this set of models to published values from LTE plane-parallel static models. We find our non-LTE spherical models consistently predict larger Lyman continuum fluxes relative to earlier models. Our models predict up to 20% more hydrogen ionizing flux and up to 125% more neutral helium ionizing flux compared to earlier models, particularly for model O stars with Teff < 36,000 K.


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