Program: GS-2012B-Q-70

Extending the current census of young nearby associations toward lower masses is essential to study the IMF at a few Myr down to substellar masses and understand the evolution and atmospheres of young brown dwarfs. Based on the proper motions and photometric properties of a large sample of red stars derived from a correlation of 2MASS with WISE, we identified 260 highly probable late- type (> M5) members of the Beta Pictoris and TW Hydrae moving groups and Tucana-Horologium association. As the youth (i.e. low surface gravity) of such objects should be apparent from some atomic lines (e.g. NaI, KI, FeH, CaH) and the strength of VO bands in their visible spectrum, we propose to use GMOS-South to obtain red optical spectra and confirm the membership of 55 candidates visible in the southern hemisphere this semester. This program will unveil a significant population of young brown dwarfs, down to the planetary mass regime, in close-by young moving groups, providing high-quality template spectra as benchmarks for evolutionary models.