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A&A 402, 701-712 (2003)
DOI: 10.1051/0004-6361:20030252
Evolutionary models for cool brown dwarfs and extrasolar giant planets. The case of HD 209458
I. Baraffe1, 2, G. Chabrier1, T. S. Barman3, F. Allard1 and P. H. Hauschildt41 C.R.A.L (UMR 5574 CNRS), École Normale Supérieure, 69364 Lyon Cedex 07, France
e-mail: ibaraffe,chabrier,fallard@ens-lyon.fr
2 Max-Planck-Institut für Astrophysik, Karl-Schwarzschildstr.1, 85748 Garching, Germany
3 Department of Physics, Wichita State University, Wichita, KS 67260-0032, USA
e-mail: travis.barman@wichita.edu
4 Hamburger Sternwarte, Gojenbergsweg 112, 21029 Hamburg, Germany
e-mail: phauschildt@hs.uni-hamburg.de
(Received 27 November 2002 / Accepted 18 February 2003 )
Abstract
We present evolutionary models for cool brown dwarfs
and extra-solar giant planets. The models reproduce the main trends
of observed methane dwarfs in near-IR color-magnitude diagrams.
We also present evolutionary models for irradiated planets,
coupling for the first time irradiated atmosphere profiles and inner
structures. We focus on HD 209458-like systems and show that
irradiation effects can substantially affect the radius of
sub-jovian mass giant planets.
Irradiation effects, however, cannot alone explain the large observed radius
of HD 209458b. Adopting assumptions which optimise irradiation effects
and taking into account the extension of the outer atmospheric
layers, we still find ~20% discrepancy between observed
and theoretical radii.
An extra source of energy seems to be required
to explain the observed value of the first transit planet.
Key words: planetary systems -- stars: brown dwarfs -- stars: evolution -- stars: individual (HD 209458)
Offprint request: I. Baraffe, ibaraffe@ens-lyon.fr
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