Magnetic mixing and the Arcturus problem

A model for main-sequence mixing driven by the buoyancy of magnetic flux tubes is proposed, and the effect of such a process on the CNO isotopes is investigated. Such a mixing scheme applied to a 2.0M/sub sun/ model is used to predict the ratios /sup 14/N//sup 15/N, /sup 16/O//sup 17/O, /sup 16/O//sup 18/O, and C/O for any observed combination of /sup 12/C//sup 13/C and C/N. Unlike meridional mixing, the penetration depth of magnetic mixing depends critically on the early history of the star. Therefore, for a given /sup 13/C enchancement, the /sup 14/N enhancement may vary making magnetic mixing a viable model both for stars with moderate /sup 13/C and /sup 14/N enhancement such as ..beta.. Gem and for stars with a large /sup 13/C enhancement and a low /sup 14/N enhancement such as ..cap alpha.. Boo.