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          Institute: MPI für Astrophysik     Collection: Stellar Astrophysics     Display Documents

ID: 12173.0, MPI für Astrophysik / Stellar Astrophysics
New grids of ATLAS9 atmospheres I: Influence of convection treatments on model structure and on observable quantities
Authors:Heiter, U.; Kupka, F.; van't Veer-Menneret, C.; Barban, C.; Weiss, W. W.; Goupil, M. J.; Schmidt, W.; Katz, D.; Garrido, R.
Date of Publication (YYYY-MM-DD):2002
Title of Journal:Astronomy & Astrophysics
Journal Abbrev.:Astron. Astrophys.
Issue / Number:2
Start Page:619
End Page:636
Review Status:Peer-review
Audience:Experts Only
Abstract / Description:We present several new sets of grids of model stellar atmospheres computed with modified versions of the ATLAS9 code. Each individual set consists of several grids of models with different metallicities ranging from [M/H] = 2.0 to +1.0 dex. The grids range from 4000 to 10 000 K in T-eff and from 2.0 to 5.0 dex in log g. The individual sets differ from each other and from previous ones essentially in the physics used for the treatment of the convective energy transport, in the higher vertical resolution of the atmospheres and in a finer grid in the (T-eff, log g) plane. These improvements enable the computation of derivatives of color indices accurate enough for pulsation mode identification. In addition, we show that the chosen vertical resolution is necessary and sufficient for the purpose of stellar interior modelling. To explain the physical differences between the model grids we provide a description of the currently available modifications of ATLAS9 according to their treatment of convection. Our critical analysis of the dependence of the atmospheric structure and observable quantities on convection treatment, vertical resolution and metallicity reveals that spectroscopic and photometric observations are best represented when using an inefficient convection treatment. This conclusion holds whatever convection formulation investigated here is used, i.e. MLT(alpha = 0.5), CM and CGM are equivalent. We also find that changing the convection treatment can lead to a change in the effective temperature estimated from Stromgren color indices from 200 to 400 K.
Free Keywords:stars : atmospheres; stars : fundamental parameters; stars : variables delta Scuti stars; convection
External Publication Status:published
Document Type:Article
Communicated by:N. N.
Affiliations:MPI für Astrophysik/Hydrodynamics
External Affiliations:Univ Vienna, Inst Astron, Turkenschanzstr 17, A-1180 Vienna,; Austria; Univ Vienna, Inst Astron, A-1180 Vienna, Austria; Case Western Reserve Univ, Dept Astron, Cleveland, OH 44106 USA; Observ Paris, F-92195 Meudon, France; Natl Solar Observ, Tucson, AZ 85719 USA; Max Planck Inst Astrophys, D-85741 Garching, Germany; CSIC, Inst Astrofis Andalucia, E-18080 Granada, Spain
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