An Asymptotic Giant Branch Star Survey in the Small Magellanic Cloud

Photographic V- and I-band photometry of a 0.8 sq deg region in the Small Magellanic Cloud is presented. The V - I color index is used to identify the candidate asymptotic giant branch (AGB) stars in this field, and spectroscopic observations are obtained of all of the latter with M(bol) of less than -5.5. The majority prove to be of spectral type K4 or K5, with only one C star in the sample. It is suggested that these earlier type giants are young, massive supergiants formed within the last few million years. A comparison with the LMC shows that the two systems have nearly identical AGB luminosity functions, suggesting that the relative star formation rates have been similar. Finally, while these radial velocity data show the well-known bimodal distribution, the width of the giant branch in the color-magnitude diagram suggests that the depth of the SMC along the line of sight is only about 5 kpc.