Lithium depletion and the rotational history of exoplanet host stars
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 (≥5 Myr) may be a necessary condition for massive planet formation/migration.
- Publication:
-
Astronomy and Astrophysics
- Pub Date:
- October 2008
- DOI:
- 10.1051/0004-6361:200810574
- arXiv:
- arXiv:0808.3917
- Bibcode:
- 2008A&A...489L..53B
- Keywords:
-
- planetary systems: formation;
- stars: rotation;
- stars: abundances;
- stars: pre-main sequence;
- accretion;
- accretion disks;
- hydrodynamics;
- Astrophysics
- E-Print:
- Astronomy and Astrophysics (2008) 0