The Host Stars of Extrasolar Planets Have Normal Lithium Abundances

The lithium abundances of planet-harbouring stars have been compared with those of open clusters and field stars. Young (chromospherically active) and subgiant stars have been eliminated from the comparison because they are at different stages of evolution and Li processing to the planet-harbouring stars, and hence have systematically higher Li abundances. The analysis showed that the Li abundances of the planet-harbouring stars are indistinguishable from those of non-planet-harbouring stars of the same age, temperature, and composition. This conclusion is opposite to that arrived at by Gonzalez & Laws (2000); it is believed that the field star sample used by them contained too wide a range of ages, evolutionary types, and temperatures to be accommodated by the model they adopted to describe the dependence on parameters. Li does not appear set to provide key insights into the formation and evolution of planetary systems.