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

In English

Författare

  • 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.

Publiceringsår

2005

Språk

Engelska

Sidor

424-439

Publikation/Tidskrift/Serie

Astrophysical Journal

Volym

633

Issue

1

Dokumenttyp

Artikel i tidskrift

Förlag

American Astronomical Society

Ämne

  • Astronomy, Astrophysics and Cosmology

Nyckelord

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

Status

Published

ISBN/ISSN/Övrigt

  • ISSN: 0004-637X