ASCA observations of the NGC 2264 molecular cloud

We have made ASCA observations of the molecular cloud associated with NGC 2 264, and detected nine and five sources in the soft and hard X-ray band ima ges, respectively. Most of them are identified with known pre-main-sequence stars or protostellar objects. Two Class I sources with intermediate lumin osities and one Class II source associated with molecular outflow are promi sing candidates for X-ray emitters. An optically thin hot-plasma model with two components can reproduce the GIS X-ray spectra, including both of the Class I sources. The hard X-rays probably arise from these Class I sources, and are intrinsically very luminous, > 10(32) erg s(-1) in the 0.7-10.0 ke V energy band, and their luminosities lie between low-mass Class I sources and that of the W 3 massive core region. Since near-infrared survey data re veal that Class I sources are surrounded by embedded young clusters, the so ft X-ray components could be explained by aggregates of low-mass pre-main-s equence stars.