Lithium in a cool red giant member of the globular cluster NGC 362

A surprisingly strong Li I lambda 6707 feature has been identified in a red giant member of the globular cluster NGC 362. This giant, V2, is located near the tip of the red giant branch and could be either a first-ascent red giant or on the asymptotic giant branch. An abundance analysis finds the lithium abundance to be log epsilon(Li) = 1.2 +/-. 0.2. Since almost all low-mass giants have destroyed and diluted their photospheric lithium abundances to much lower levels, the source of lithium in star V2 is a mystery. The solution to this mystery is suggested to reside in two possible mechanisms. The proposed deep-mixing mechanism called "cool bottom processing" can account for the observed lithium at this giant's luminosity [log (L/L.) = 3.3] if the parameterized mixing speed, measured as log(dM/dt), is similar to-5.5 (in units of M. yr(-1)). An alternative source of the excess lithium could be the ingestion, into the red giant's convective envelope, of an similar to 0.04 M. object with an assumed undepleted, typical halo lithium abundance of log epsilon(Li) = 2.2.