Spectroscopic Observations of SC Stars

Abstract

A search has been carried out for stars similar to the SC type star UY Cen, and twelve are listed in Table I. The six stars newly assigned to the group were selected for observation on the basis of an objective prism survey by Henize. The spectroscopic characteristics defining the group are discussed and the differences from CS stars like R CMi noted. Radial velocities are listed for eight SC stars (making a total of ten with known velocity). A rough estimate of the absolute magnitude |$({M}_\text{v}\,\sim\,-2)$| and a velocity dispersion of |$31\,\pm \,7\,\text{km}\,\text{s}^{-1}$| are derived. These figures suggest that the stars are giants of intermediate age and mass. The nine stars of the group which have been adequately studied are all lithium rich, one of them superlithium rich. In contrast both the C and S types apparently each contain lithium poor stars. The frequency of superlithium rich stars also appears to be higher in the combined SC and CS group (2 out of 18 stars) than in either the C or the S classes. The wavelength of the lithium line in SC stars agrees with that expected for Li 7 . Theoretical suggestions by Cameron and Fowler on lithium production in late type giants are briefly discussed in the light of these observations.