Program: GS-2006A-Q-55

Title:A Spectroscopic Study of Young 5-100 M$_{\rm J}$ Objects in Lupus and Cham II
PI:Daniel Jaffe
Co-I(s): Katelyn Allers, Greg Doppmann

Abstract

By studying brown dwarfs when they are young and bright, we can investigate the nature of objects with extremely low masses and test our understanding of star formation and protostellar evolution at one extreme of the mass range. We have used very deep IJHK imaging combined with Spitzer 3.5-24 $\mu$m observations to identify a sample of young brown dwarfs in nearby star forming regions. The presence of circum-object disks confirms the youth of these sources and their association with the parent clouds. The objects have luminosities from 10$^{-4}$ to 10$^{-1}$ L$_{\odot}$ with a substantial fraction at or below the lowest luminosities previously reported for young brown dwarfs. For ages of 1-3$\times 10^6$ years, the lowest mass objects are $\sim$2M$_J$ and half are below the deuterium burning limit. We will use GNIRS to take R=1700 JHK spectra of a subsample of these young brown dwarfs. We will use the spectroscopic results to produce a low-gravity sequence for L-type objects. We will test models of young BD atmospheres in a regime where uncertain molecular opacities and the effects of dust settling have not been confronted with observations. We will use the spectroscopic and photometric data for the whole sample to place these young brown dwarfs in an HR diagram to investigate the evolutionary state of the extended low mass population in star forming clouds.