Distribution of spectral types in the LMC clusters.

The distribution of spectral types in 42 LMC globular star clusters covering all evolutionary ages was determined using objective prism spectra taken with the 1.2-m U.K. Schmidt Telescope in Australia. The derived spectral type distributions show that the clusters can be divided into five age categories from about 10 to the 7th to more than 10 to the 9th yr. Several clusters were found to contain carbon stars with C/M ratios ranging from 0.07 to 0.4. These ratios were compared with those found for the SMC clusters and the Milky Way. It was found that the stars of the LMC exhibit a smaller range of C/M ratios than in the SMC, but larger than in the Galaxy, thus providing an additional test of the theoretical models predicting a correlation between the C/M ratio and metal content. It was also found that the majority of young clusters were embedded in older fields, while the intrmediate clusters were embeded in younger fields, and the remote old clusters were embedded in a stellar content of similar age.