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On the limb darkening, spectral energy distribution, and temperature structure of procyon

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Author

  • JP Aufdenberg
  • Hans-Günter Ludwig
  • P Kervella

Summary, in English

We have fit synthetic visibilities from three-dimensional ((COBOLD)-B-5+PHOENIX) and one-dimensional (PHOENIX, ATLAS 12) model stellar atmospheres of Procyon (F5 IV) to high-precision interferometric data from the VLT Interferometer (K band) and from the Mark III interferometer (500 and 800 nm). These data sets provide a test of theoretical wavelength-dependent limb-darkening predictions. The work of Allende Prieto et al. has shown that the temperature structure from a spatially and temporally averaged three-dimensional hydrodynamic model produces significantly less limb darkening at 500 nm relative to the temperature structure of a one-dimensional MARCS model atmosphere with a standard mixing-length approximation for convection. Our direct fits to the interferometric data confirm this prediction. A one-dimensional ATLAS 12 model with " approximate overshooting" provides the required temperature gradient. We show, however, that one-dimensional models cannot reproduce the ultraviolet spectrophotometry below 160 nm with effective temperatures in the range constrained by the measured bolometric flux and angular diameter. We find that a good match to the full spectral energy distribution can be obtained with a composite model consisting of a weighted average of 12 one-dimensional model atmospheres based on the surface intensity distribution of a three-dimensional granulation simulation. We emphasize that one-dimensional models with overshooting may realistically represent the mean temperature structure of F-type stars such as Procyon, but the same models will predict redder colors than observed because they lack the multicomponent temperature distribution expected for the surfaces of these stars.

Publishing year

2005

Language

English

Pages

424-439

Publication/Series

Astrophysical Journal

Volume

633

Issue

1

Document type

Journal article

Publisher

American Astronomical Society

Topic

  • Astronomy, Astrophysics and Cosmology

Keywords

  • temperatures)
  • fundamental parameters (colors
  • stars :
  • stars : atmospheres
  • convection
  • methods : numerical
  • stars : individual
  • (Procyon)
  • techniques : interferometric

Status

Published

ISBN/ISSN/Other

  • ISSN: 0004-637X