2MASS observations of spectroscopically identified extragalactic C stars

Abstract

We matched spectroscopically identified C stars (from low resolution objective prism surveys) in the Magellanic Clouds with 2MASS sources. We confirm that C stars show a large spread in absolute magnitudes, even in the Ks band. We show that the I and Ks magnitude distributions of a population of C stars (in the LMC) have a similar narrow dispersion if the C stars are selected in a well defined color range. Using magnitude and color criteria, we employ the 2MASS data to identify 26 C stars in the the Fornax dwarf spheroidal galaxy. The mean Ks magnitude and the mean bolometric magnitude of C stars are found to be slightly brighter in the LMC and SMC when compared to those of the Fornax dwarf spheroidal galaxy. The difference could be explained by ages or/and abundance differences.