BROWN DWARFS IN THE PLEIADES CLUSTER CONFIRMED BY THE LITHIUM TEST

We present Keck Observatory 10 m telescope spectra of the two Pleiades brown dwarfs, Teide 1 and Calar 3, showing a clear detection of the L i 670.8 nm resonance line. In Teide 1, we have also obtained evidence for the presence of the subordinate line at 812.6 nm. A high Li abunda nce [log N(Li) greater than or equal to 2.5], consistent with little i f any depletion, is inferred from the observed lines. Since Pleiades b rown dwarfs are unable to burn Li, the significant preservation of thi s fragile element confirms the substellar nature of our two objects. R egardless of their age, their low luminosities and Li content place Te ide 1 and Calar 3 comfortably in the genuine brown dwarf realm. Given the probable age of the Pleiades cluster, their masses are estimated a t 55 +/- 15 M(J).