The CNO Isotopes: Deep Circulation in Red Giants and First and Second Dredge-up

  title={The CNO Isotopes: Deep Circulation in Red Giants and First and Second Dredge-up},
  author={Arnold I. Boothroyd and I. Juliana Sackmann},
  journal={The Astrophysical Journal},
It is demonstrated that deep circulation mixing below the base of the standard convective envelope, and the consequent "cool bottom processing" (CBP) of the CNO isotopes, can reproduce the trend with stellar mass of the 12C/13C observations in low-mass red giants. (This trend is opposite to what is expected from standard first dredge-up.) Our models assume that extra mixing always reaches to the same distance in temperature from the H-burning shell and that CBP begins when the H-burning shell… 
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