Criteria for the 12C/13C ratio of carbon stars by line profiles of 13CN

The estimation of the C-12/C-13 ratio by the criteria using line profiles of 13CN may be of some importance through the whole range of spectral subtypes of carbon stars. For this purpose, the spectrographic observation of some carbon stars in the spectral wave length range from (lambda) 7900 to (lambda) 7960 was carried out at the Okayama Observatory, and the data are presented in this paper. Some data obtained at the Palomer Observatory are also shown in a table. The line profiles of the microphotometric tracing of data showed that the C-12/C-13 ratio was less than 10 in all J-type stars and was larger than 20 in all other carbon stars. The ratio C-12/C-13 was 16 in HD156074 which shows (lambda) 7935.63 feature only. (Kato, T.)