Observable Consequences of Star Formation in Molecular Clouds

Abstract

The solar neighborhood is probably the smoothed-over-time accumulation of all the stars born in molecular clouds since the formation of the disk, but in order to reproduce the local mass function it is necessary to postulate also that low-mass stars can be produced without OB stars in the conventional proportions. A few extraordinarily dense clusters of young stars in molecular clouds are known, especially that around the Orion Trapezium, but it is not known whether such clusters are the source of low-mass stars in the quantities required. The color-magnitude diagram of the Trapezium Cluster is that of a young cluster containing stars of ages up to that of an average giant molecular cloud, a few 10⁷ years. A few stars in the solar neighborhood may be low-mass, still pre-main-sequence, products of recently dissipated clouds.