Formation of low mass stars and brown dwarfs

Abstract

Despite the recent identification of a few brown dwarfs and extremely low-mass stars, their abundance does not appear to be sufficiently large for them to be the major contributors of the Galactic halo potential. We examine here the formation of brown dwarf and low mass stars under three different conditions. We show that the first generation metal poor stars, formed from the fragmentation of the protogalactic clouds, are likely to be massive and short lived. The formation efficiency of brown dwarfs is also likely to be low in present-day molecular cloud cores. Finally, we show that the formation of brown dwarfs may require the fragmentation of protostellar disks which differs from the path of protoplanetary formation.