A super-Li rich turnoff star in NGC 6397 - the puzzle persists
  This presentation focuses on a recently discovered super-Li rich turnoff star
in the old, metal poor globular cluster NGC 6397 (Koch et al. 2011, ApJL, 738,
L29). Its unusually high NLTE lithium abundance of A(7Li) = 4.21, the highest
Li enhancement found in a Galactic GC dwarf star to date, has defied any
unambiguous explanation through canonical enrichment channels. Spectra of the
star show no convincing evidence for binarity, and measured line strengths and
chemical element abundance ratios are fully compatible with other turnoff stars
in this GC, seemingly ruling out mass transfer from an AGB companion as origin
of the high A(Li). A possible cause is an interaction with a red giant that has
undergone cool bottom processing.
