Understanding the Li production in AGB stars: the J-type stars

A full abundance analysis have been carried out in 12 galactic J-stars. The analysis shows: a) C-12/C-13 ratios are low, b) the abundance of s-process and rare-earth elements with respect to the stellar metallicity is nearly-solar, [< heavy > /Fc] = 0.10 +/- 0.11 c) Tc is not present in most of the stars although upper limits are placed in WZ Cas and WX Cyg, probably two SC-type stars, and d) all the stars are Li-rich, log is an element of(Li) > 1. The location of J-stars in ail empirical H-R diagram when compared with that of the normal N-type carbon stars, suggests that J-stars may be in the early-AGB phase. The different mechanism proposed to be responsible of this Li production are briefly discussed.