Convection and 6Li in the atmospheres of metal-poor halo stars

Based on 3D hydrodynamical model atmospheres computed with the CO (BOLD)-B-5 code and 3D non-LTE (NLTE) line c formation calculations, we study the effect of the convection-induced line asymmetry on the derived Li-6 abundance for a range in effective temper attire gravity, and metallicity covering the stars of the Asplund el at (2006) sample. When the asymmetry effect is taken into account for this sample of stars, the resulting Li-6/Li-7 ratios are reduced by about 1 5% on average with respect to the isotopic ratios determined by Asplund et at (2006) This purely theoretical collection diminishes the number of significant Li-6 detections from 9 to 4 (2 sigma criterion), sigma from 5 to 2 (3 sigma criterion) In view of this result the existence of a Li-6 plateau appeals questionable A careful reanalysis of individual objects by fitting the observed lithium 6707 angstrom doublet both with 3D NUPE and 1D LTE synthetic line profiles eolith ins that ;the inferred Li-6 abundance is systematically lower when using 3D NLTE instead of 1D LTE line fitting Nevertheless, halo stars with unquestionable Li-6 detection do exist, even if anal) zed in 3D-NLTE, the most prominent example being HD84937