Abundances in J-Type Carbon Stars

It has been found by Utsumi(1985a,b) that in J-type carbon stars of C4-5 and WZ Cas(C9,2J Li), abundances of s-process elements with respect to Fe are nearly normal, while in normal carbon stars of C5-8, heavy metals are overabundant by factors of 10-100, and rare-earth elements are overabundant by a factor of about 10. In the MK system, most J-type stars are classified as C4-5,4-5 stars which show very strong C2 and CN bands. Yamashita(l972,1975) classified many C7-9 stars most of which are CS or SC stars. His classification of C7-9J stars is mainly based on Cl2C13(0,1)band at 6168 A, C13N(4,0)band at 6260 A, and LiI 6708 A line. In most of C7-9 stars, lines of s-prooess elements are greatly enhanced. It is a question if in all J-type stars abundances of s-process elements are nearly normal or not.