Lithium depletion in solar-like stars: no planet connection

¹ Max Planck Institute for Astrophysics, Postfach 1317, 85741 Garching, Germany e-mail: [pbaumann,ivan,asplund]@mpa-garching.mpg.de
² Centro de Astrofisica da Universidade do Porto, Rua das Estrelas, 4150-762 Porto, Portugal e-mail: jorge@astro.up.pt
³ European Southern Observatory(ESO), Karl-Schwarzschild-Str. 2, 85748 Garching, Germany e-mail: klind@eso.org

Received: 2 June 2010
Accepted: 24 June 2010

Abstract

We have determined precise stellar parameters and lithium abundances in a sample of 117 stars with basic properties very similar to the Sun. This sample selection reduces biasing effects and systematic errors in the analysis. We estimate the ages of our sample stars mainly from isochrone fitting but also from measurements of rotation period and X-ray luminosity and test the connection between lithium abundance, age, and stellar parameters. We find strong evidence for increasing lithium depletion with age. Our sample includes 14 stars that are known to host planets and it does not support recent claims that planet-host stars have experienced more lithium depletion than stars without planets. We find the solar lithium abundance normal for a star of its age, mass, and metallicity. Furthermore, we analyze published data for 82 stars that were reported to support an enhanced lithium depletion in planet hosts. We show that those stars in fact follow an age trend very similar to that found with our sample and that the presence of giant planets is not related to low lithium abundances. Finally, we discuss the systematic biases that led to the incorrect conclusion of an enhanced lithium depletion in planet-host stars.