Lithium Abundances in a Sample of Planet Hosting Dwarfs

This work presents a homogeneous determination of lithium abundances in a large sample of giant-planet hosting stars (N=117), and a control sample of disk stars without detected planets (N=145). The lithium abundances were derived using a detailed profile fitting of the Li I doublet at lambda 6708 A in LTE. The planet hosting and comparison stars were chosen to have significant overlap in their respective physical properties, including effective temperatures, luminosities, masses, metallicities and ages. The combination of uniform data and homogeneous analysis with well selected samples, makes this study well-suited to probe for possible differences in the lithium abundances found in planet hosting stars. An overall comparison between the two samples reveals no obvious differences between stars with and without planets. Closer examination of the behavior of the Li abundances over a narrow range of effective temperature (5700 K < Teff < 5850 K) indicates subtle differences between the two stellar samples; this temperature range is particularly sensitive to various physical processes that can deplete lithium. In this Teff range planet hosting stars have lower Li abundances (by ~0.26 dex on average) than the comparison stars, although this segregation may be influenced by combining stars from a range of ages, metallicities and masses. When stars with very restricted ranges in metallicity ([Fe/H] = 0.00 to +0.20 dex) and mass (M ~ 1.05 - 1.15 Msun are compared, however, both stars with and without planets exhibit similar behaviors in the lithium abundance with stellar age, suggesting that there are no differences in the lithium abundances between stars with planets and stars not known to have planets.