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C. Barnbaum (Valdosta State University), R. P. S. Stone (Lick Observatory, UCSC), M. Groenewegen (Max Planck Institut fur Astrophysik), P. C. Keenan (Ohio State University)
We have obstained moderate-resolution visible spectra of 12 infrared carbon stars. Infrared carbon stars are heavily enshrouded by circumstellar dust whereas optical carbon stars are much less reddened, and the relation between these two groups is not clear. We have compared these spectra with those of optical carbon stars using the revised MK system. Until now only optical carbon stars have been studied spectroscopically. The relation between these two varieties of carbon star is poorly understood in terms of a sequence in mass or evolutionary phase. Our measurements of the spectra give effective temperatures and relative lithium abundances. The importance of determing a mass range of all carbon stars concerns not only stellar interior theory but also mass return to the ISM.