Fluorine Abundance Variations as a Signature of Enhanced Extra Mixing in   Red Giants of the Globular Cluster M4
  We show that enhanced extra mixing in low-mass red giants can result in a fluorine abundance that is correlated with abundance variations of other elements participating in H burning, such as C, N, O and Na. This finding is used to explain the fluorine abundance variations recently found in bright red giants of the globular cluster M4. 
Pavel A. Denissenkov (1,2), Marc Pinsonneault (1), and Donald M.   Terndrup (1) ((1) The Ohio State University, (2) On leave...