Observational Clues to Brown Dwarf Origins

Abstract

Over the past year, we have conducted a multi-faceted program to investigate the origin and early evolution of brown dwarfs. Using high-resolution Keck optical spectra of ∼30 objects near and below the substellar boundary in several star-forming regions, we present compelling evidence for a T Tauri-like accretion phase in young brown dwarfs. Our systematic study of infrared L ¹-band (3.8μm) disk excess in ∼50 spectroscopically confirmed young very low mass objects reveal that a significant fraction of brown dwarfs harbor disks at a very young age. Their inner disk lifetimes do not appear to be vastly di erent from those of disks around T Tauristars. Taken together, our findings are consistent with a common origin for most low-mass stars, brown dwarfs and isolated planetary mass objects.