Lithium Production in Hot Advection-dominated Accretion Flows in Soft X-Ray Transients

摘要

High Li abundances have been reported in the late-type secondaries of five soft X-ray transients (SXTs): V404 Cyg, A0620-00, GS 2000+25, Nova Mus 1991, and Cen X-4. Since Li is likely to be depleted in stars of this type, the origin of the Li is puzzling. Li has not been seen in similar secondaries of cataclysmic variables, which suggests that the high Li abundance is not due to an anomalous sup- pression of Li depletion in close binaries. SXTs in the quiescent state have been modeled in terms of hot advection-dominated accretion flows (ADAFs), in which the ions are essentially at virial temperature. At such temperatures, Li production via α-α spallation is possible.