Lithium in very metal-poor thick disc stars

A search for lithium is performed on seven metal-poor dwarfs with metallicities ranging from [Fe/H] = -1.5 down to [Fe/H] = -3.0 but showing disc-like kinematics. These stars belong to the metal-poor tail of the Galactic thick disc, and they may be also the result of an accretion event. The Li 6707.8-Angstrom line is present in all seven dwarfs. The weighted average of the Li abundance for the stars is A(Li) = 2.20 +/- 0.06 and is consistent within the errors with the plateau Li abundance of A(Li) = 2.24 +/- 0.012 found in genuine halo stars in the same range of metallicities. One of the stars, CS 22182-24, shows a somewhat lower Li abundance [A(Li) = 1.6 +/- 0.40] and is a candidate for being a Li-poor star. Whether this group of stars belongs to the oldest stars in the disc or the old population of an external galaxy accreted by the Milky Way, the present observations provide support for the universality of a pre-Galactic Li abundance as observed in the Galactic halo stars.