EDP Sciences
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Free access
Issue
A&A
Volume 489, Number 3, October III 2008
Page(s) L53 - L56
Section Letters
DOI http://dx.doi.org/10.1051/0004-6361:200810574
Published online 11 September 2008


A&A 489, L53-L56 (2008)
DOI: 10.1051/0004-6361:200810574

Letter

Lithium depletion and the rotational history of exoplanet host stars

J. Bouvier

Laboratoire d'Astrophysique, Observatoire de Grenoble, Université J. Fourier, CNRS, UMR 5571, BP 53, 38041 Grenoble Cedex 9, France
    e-mail: jbouvier@obs.ujf-grenoble.fr

Received 11 July 2008 / Accepted 26 August 2008

Abstract
Context. It has been reported that exoplanet host stars are lithium depleted compared to solar-type stars without detected massive planets.
Aims. We investigate whether enhanced lithium depletion in exoplanet host stars may result from their rotational history.
Methods. We have developed rotational evolution models for slow and fast solar-type rotators from the pre-main sequence (PMS) to the age of the Sun and compare them to the distribution of rotational periods observed for solar-type stars between 1 Myr and 5 Gyr.
Results. We show that slow rotators develop a high degree of differential rotation between the radiative core and the convective envelope, while fast rotators evolve with little core-envelope decoupling. We suggest that strong differential rotation at the base of the convective envelope is responsible for enhanced lithium depletion in slow rotators.
Conclusions. We conclude that lithium-depleted exoplanet host stars were slow rotators on the zero-age main sequence (ZAMS) and argue that slow rotation results from a long lasting star-disk interaction during the PMS. Altogether, this suggests that long-lived disks ($\geq$5 Myr) may be a necessary condition for massive planet formation/migration.


Key words: planetary systems: formation -- stars: rotation -- stars: abundances -- stars: pre-main sequence -- accretion, accretion disks  -- hydrodynamics



© ESO 2008

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