Name/Affiliation: Emily C. Martin (UCLA)
Analysis of M and L dwarf surface gravities in the NIRSPEC Brown Dwarf Spectroscopic Survey
Using previously published gravity-sensitive indices, we report on the analysis of near-infrared spectra for ~200 M and L dwarfs. This allows us to disentangle the degeneracy between temperature and age for brown dwarfs of various masses. The spectra were obtained as part of the Brown Dwarf Spectroscopic Survey (BDSS) using NIRSPEC at the Keck Observatory and have a resolving power of R~2000 in the J band. By comparing a subset of the BDSS database with established gravity indices at lower spectral resolution, we demonstrate that these indices also work well for higher resolution spectra. We then apply these techniques to the entire set of M and L dwarfs in the BDSS to classify the diverse surface gravities of this large sample in a consistent manner. This analysis provides new age estimates for many M and L dwarfs, which will guide future studies of the young and old brown dwarf populations.