Theory of extended stellar atmospheres. II. A grid of static spherical models for O stars and planetary nebula nuclei

Journal Article · Sat Nov 15 04:00:00 EST 1975 · Astrophys. J., v. 202, no. 1, pp. 92-113

DOI:https://doi.org/10.1086/153955· OSTI ID:4113737

Kunasz, P B; Hummer, D G; Mihalas, D

Spherical static non-LTE model atmospheres are presented for stars with M/M/sub sun/=30 and 60 at various points on their evolutionary tracks, and for some nuclei of planetary nebulae at two points of a modified Harman-Seaton sequence. The method of Mihalas and Hummer was employed, which uses a parametrized radiation force multiplier to simulate the force of radiation arising from the entire line spectrum. However, in the present work the density structure computed in the LTE models was held fixed in the calculation of the corresponding non-LTE models; in addition, the opacity of an ''average light ion'' was taken into account. The temperatures for the non-LTE models are generally lower, at a given depth, than for the corresponding LTE models when T/ sub eff/<45,000 K, while the situation is reversed at higher temperatures. The continuous energy distributions are generally flattened by extension. The Lyman jump is in emission for extended models of massive stars, but never for the models of nuclei of planetary nebulae (this is primarily a temperature effect). The Balmer jumps are always in absorption. The Lyman lines are in emission, and the Balmer lines in absorption; He ii lambda4686 comes into emission in the most extended models without hydrogen line pumping, showing that it is an indicator of atmospheric extension. Very severe limb darkening is found for extended models, which have apparent angular sized significantly smaller than expected from the geometrical size of the star. Extensive tables are given of monochromatic magnitudes, continuum jumps and gradients, Stomgren-system colors, monochromatic extensions, and the profiles and equivalent widths of the hydrogen lines for all models, and of the He ii lines for some of the 60 M/sub X/ models. (AIP)

• Research Organization: Univ. of Colorado, Boulder
• Sponsoring Organization: USDOE
• NSA Number: NSA-33-018031
• OSTI ID: 4113737
• Journal Information: Astrophys. J., v. 202, no. 1, pp. 92-113, Journal Name: Astrophys. J., v. 202, no. 1, pp. 92-113; ISSN ASJOA
• Country of Publication: United States
• Language: English

Related Subjects

*STELLAR ATMOSPHERES-- SPHERICAL MODEL
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PLANETARY NEBULAE
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