The Brown Dwarf Kinematics Project ( BDKP ) . II . Details on Nine Wide Common Proper Motion Very Low – Mass Companions to Nearby Stars Citation

We report on nine wide common proper motion systems containing late-type M, L, or T companions. We confirm six previously reported companions, and identify three new systems. The ages of these systems are determined using diagnostics for both stellar primaries and low–mass secondaries and masses for the secondaries are inferred using evolutionary models. Of our three new discoveries, the M3+T6.5 pair G 204-39 and SDSS J1758+4633 has an age constrained to 0.5-1.5 Gyr making the secondary a potentially useful brown dwarf benchmark. The G5+L4 pair G 200-28 and SDSS J1416+5006 has a projected separation of ∼25,000 AU making it one of the widest and lowest binding energy systems known to date. The system containing NLTT 2274 and SDSS J0041+1341 is an older M4+L0 (>4.5 Gyr) pair which shows Hα activity in the secondary but not the primary making it a useful tracer of age/mass/activity trends. Two of Department of Astrophysics, American Museum of Natural History, Central Park West at 79th Street, New York, NY 10034; jfaherty@amnh.org Massachusetts Institute of Technology, Kavli Institute for Astrophysics and Space Research, Building 37, 77 Massachusetts Avenue, Cambridge, MA 02139 Department of Physics and Astronomy, Stony Brook University Stony Brook, NY 11794-3800 Astronomy Department, California Institute of Technology, Pasadena, CA 91125 Spitzer Postdoctoral Fellow Visiting Astronomer at the Infrared Telescope Facility, which is operated by the University of Hawaii under Cooperative Agreement no. NCC 5-538 with the National Aeronautics and Space Administration, Science Mission Directorate, Planetary Astronomy Program. Center of Astrophysics and Space Sciences, Department of Physics, University of California, San Diego, CA 92093, USA Guest observer at the Kitt Peak National Observatory, which is operated by the Association of Universities for Research in Astronomy under cooperative agreement with the National Science Foundation