Name/Affiliation: William Best (Institute for Astronomy, University of Hawaii)
Building a Volume-Limited sample of L/T Transition Dwarfs with Pan-STARRS and WISE
The current census of L/T transition brown dwarfs (spectral types ~L6-T5) is a compilation of magnitude-limited surveys with varying sensitivity, spatial coverage, and spectral completeness. While ~90 L/T dwarfs within 25 pc have been found, and several individual objects have been studied in detail, many fundamental properties of the L/T transition remain poorly understood. We are building a complete, volume-limited sample of L/T transition dwarfs within 25 pc. We have searched 30,000 deg^2 in the the Pan-STARRS1 3pi and WISE all-sky surveys for brown dwarfs spanning the L/T transition. We have spectroscopically confirmed a total of 117 new L and T dwarfs (an 82\% success rate); 80 of these are L/T transition dwarfs, 30 of which have photometric distances within 25 pc. Our discoveries help to form a well-defined, robust sample of L/T dwarfs that can constrain atmospheric models and improve our understanding of the progression from dusty and cloudy L dwarfs to clear T dwarf photospheres, and better characterize the handful of extremely red late-L dwarfs that have been discovered. Our sample also provides more targets for variability searches, and for high-resolution imaging and spectral decomposition to identify L+T binaries whose colors mimic those of single L/T transition objects.