Lithium depletion in solar-like stars: no planet connection

TL;DR

This study investigates lithium depletion in solar-like stars, finding it correlates with age but not with the presence of planets, challenging previous claims of enhanced depletion in planet-hosting stars.

Contribution

The paper provides a precise analysis of lithium abundance in a carefully selected sample, demonstrating no link between planet hosting and lithium depletion, and clarifies previous misconceptions.

Findings

Lithium depletion increases with stellar age.

No significant difference in lithium levels between planet-host and non-planet-host stars.

Systematic biases affected earlier studies claiming planet-related lithium depletion.

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.