ON THE ORIGIN OF A SAMPLE OF SUSPECTED CH STARS IN THE LARGE MAGELLANIC CLOUD

We present (R - I)KC photometry based on optical spectrophotometry, an d JHK photometry for the carbon stars suspected of being CH stars disc overed by Hartwick and Cowley (1988) in the field of the LMC. These ca rbon stars are shown to be more luminous than the red giant branch tip of the Galactic Population II giants and CH stars, and therefore are not members of the old stellar population in the LMC. The mean bolomet ric magnitude for this sample is M(bol) = -5.3 while the brightest mem bers reach M(bol) = -6.2. These carbon stars are significantly bluer a nd somewhat brighter in the mean than the LMC carbon stars discovered by Blanco et al. (1980). We argue that the luminosity and color distri butions presented in this paper, as well as the kinematical properties presented by Cowley and Hartwick (1991), are consistent with the asso ciation of this sample of carbon stars with a younger population of AG B stars compared to the Blanco et al. (1980) carbon stars, possibly wi th ages near 10(8) years. The enhancement of resonance lines of s-proc essed elements as reported by Hartwick and Cowley (1988) are reminisce nt of the possible enhancements of these elements in Galactic N stars, and are consistent with the prediction of the ''third dredge-up'' pha se in the evolution of intermediate-mass AGB giants.