Low-mass stars in the orion region

Recent observational evidence shows that low-mass stars were firstly formed in molecular clouds, and that, at a later stage when massive stars were formed, the formation rate of low mass stars was still high in the Orion nebula (this paper) but decreased rapidly in NGC 2264 (Adamset al., 1983). This difference is probably caused by the effects of mass ejection and luminous radiation from the stars which were born in the previous period.In this paper, we discuss examples of low mass stars in order to find a relationship between the age and location of stars.