Incidence of heavy element enhancements among carbon stars

The correlation of spectral line strength with temperature subclass has been examined in a survey of 40 carbon stars at a dispersion of 15 Å mm -1 . The two goals of this search were (1) to determine if additional cool N-type stars can be added to the list of N stars not having enhanced s-process elements, and (2) to confirm the anticorrelation of s-process enhancements with 13 C enhancement. Among the program stars one normal carbon star was found to have no, or only minor, enhancement of heavy elements associated with the s-process. The suspicion that increased surface 13 C is accompanied by weak line strengths of s-process elements is strongly confirmed.