Carbon, nitrogen, and oxygen abundances in G and K giants.

C, N and O abundances are presented for 32 G and K giants and subgiants, where the primary indicators of abundances are: (1) the C(2) lines at 5086 and 5135 A; (2) the O I forbidden lines at 6300 and 6363 A, and (3) CN red system lines. The CNO abundances show that CN-processed material has been dredged to the surface of the giants, with the C abundance reduced, that of N increased, and O remaining unchanged. Lower mass giants are found to be C-13-rich, relative to standard predictions. Relative to the C-13-normal clump giants, a larger mass of processed material is dredged to the surface of the rich giants. This material is, however, less processed than that of the normal stars. This result is consistent with the view of the occurrence of mixing in the radiative zone between the core and the outer convection zone of a main sequence star.