Poster Abstracts

Name/Affiliation:  Elisa Delgado Mena (CAUP)

Title:  Li depletion in FG stars: planets and rotation

Light elements can give us important information about the mixing processes inside stellar interiors. However, their depletion mechanisms are not completely understood yet. A wide spread in Li and Be abundances has been observed in clusters like M67 or NGC3960 as well as in field solar type stars but it cannot be explained with standard models. In this work we present new determinations of lithium abundances for 678 main sequence stars with and without planets in the Teff range 5600-7200 K, observed inside HARPS-GTO samples or with other high-resolution spectrographs. We first study the relation of planets with Li abundances. We confirm significant differences in the Li distribution of solar twins (Teff = T? 80 K, log g = log g? 0.2 and [Fe/H] = [Fe/H]? 0.2): the full sample of planet host stars (22) shows Li average values lower than "single" stars with no detected planets (60). If we focus on subsamples with narrower ranges in metallicity and age, we observe indications of a similar result though it is not so clear for some of the subsamples. Moreover, we find indications that the amount of depletion of Li in planet-host solar-type stars is higher when the planets are more massive than Jupiter. We suggest that the presence of planets might cause additional rotationally induced mixing in the external layers of planet host stars and thus an extra Li depletion. When we move to hotter temperatures we find a group of stars that present strong depletion of Li as compared with similar stars and that are still far from the Li-dip produced near 6400K. We explore the possible cause of this effect by checking their ages and vsini values. These stars indicate that non-standard processes like rotationally-induced mixing or episodic accretion may produce strong depletion of light elements.