Use of the UK Schmidt for a Photometric Investigation of Red Stars in the Orion Nebula Molecular Complex

Abstract

As a region of recent star formation and intense stellar activity the Orion Complex extending over several square degrees is of paramount importance in the study of early evolution and activity in the stellar chromospheres of low mass stars. Although red stars form a rather inhomogeneous group, including foreground K-M dwarfs, distant K-M giants, carbon stars and a variety of reddened objects, in principle these can be separated from a combination of photometric, spectroscopic and kinematic data. The proximity of the Orion Complex and its relatively high galactic latitude mean that future astrometric and radial velocity work will yield useful kinematical information on all member stars, including the enigmatic pre-main sequence stars on the lower part of the HR diagram. For these stars, differences in spectroscopic properties, photometric behaviour, kinematics and the interstellar environment contain the key to some of the problems, presently insurmountable, in the early evolution of the entire Orion Complex.