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On Stellar Models with Blanketed Atmospheres as Boundary Conditions

Published online by Cambridge University Press:  01 December 2006

Don A. VandenBerg ,
Bengt Edvardsson ,
Kjell Eriksson ,
Bengt Gustafsson  and
Jason W. Ferguson
Don A. VandenBerg
Affiliation:
Dept. of Physics and Astronomy, University of Victoria, Victoria, B.C., V8W 3P6, Canada email: vandenbe@uvic.ca
Bengt Edvardsson
Affiliation:
Uppsala Astronomical Observatory, Box 515, SE-751 20 Uppsala, Sweden email: be@astro.uu.se, Kjell.Eriksson@astro.uu.se, bg@astro.uu.se
Kjell Eriksson
Affiliation:
Uppsala Astronomical Observatory, Box 515, SE-751 20 Uppsala, Sweden email: be@astro.uu.se, Kjell.Eriksson@astro.uu.se, bg@astro.uu.se
Bengt Gustafsson
Affiliation:
Uppsala Astronomical Observatory, Box 515, SE-751 20 Uppsala, Sweden email: be@astro.uu.se, Kjell.Eriksson@astro.uu.se, bg@astro.uu.se
Jason W. Ferguson
Affiliation:
Department of Physics, Wichita State University, Wichita, Kansas 67260-0032, U.S.A. email: jason.ferguson@wichita.edu
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Abstract

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The impact on the predicted Teff scale of using the latest MARCS model atmospheres, instead of a fixed atmospheric structure (e.g., the gray T–τ relation) is examined. The former were fitted to stellar interior models at both the photosphere and at τ = 100 to determine the sensitivity of evolutionary tracks and isochrones for [Fe/H] = 0.0 and −2.0 to the chosen fitting point. In the case of solar abundances, the Teff of the giant branch varied by up to 100–150 K, depending on how the outer layers were treated. Much smaller variations were found for metal-poor giants (or main-sequence stars). Interestingly, models for the low solar Z favored by Asplund et al. (Z=0.0125) were unable to reproduce the gap near the turnoff in the C-M diagram of the old open cluster M 67, in contrast to models that assume Z=0.0188.

Keywords

Sun: abundancesstars: abundancesstars: atmospheresstars: evolution
Type
Contributed Papers
Information
Proceedings of the International Astronomical Union , Volume 2 , Symposium S241: Stellar Populations as Building Blocks of Galaxies , December 2006 , pp. 23 - 27
Copyright
Copyright © International Astronomical Union 2007

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