SSSPM J0829-1309: a new nearby L dwarf detected in SuperCOSMOS Sky Surveys

Abstract

The SuperCOSMOS Sky Surveys provide a complete coverage of the Southern sky in three passbands (photographic B_J, R and I) and at different epochs (Hambly et al. 2001a,b,c). These data are the basis for a new high proper motion survey which aims at finding extremely red nearby dwarf stars and brown dwarfs. One of the first candidates, which is relatively bright (I=16) but very red (R-I=2.8, B_J-R=3.6), was detected in the equatorial zone by its large proper motion of 0.56 arcsec/yr. Spectroscopic follow-up observations with the 2.2m telescope of the Calar Alto Observatory classified this object as L2 dwarf very similar to the first free-floating L dwarf Kelu1 also discovered in a proper motion survey by Ruiz et al. (1997). If we assume SSSPMJ0829-1309 to have the same luminosity as Kelu1, we get a distance estimate for the new L dwarf of about 12pc since it is about one magnitude brighter than Kelu1 in the SSS I and R bands. This makes SSSPMJ0829-1309 one of the nearest objects of its class, well suited for detailed investigations. We present a brief overview of all known nearby (d<20pc) southern L dwarfs and give first proper motion values for DENIS-PJ0255-47 and SDSSpJ1326-00 and an improved proper motion for LHS102B.