Astron. J., 142, 64 (2011/August-0)
1 µm excess sources in the UKIDSS. I. Three T dwarfs in the Sloan digital sky survey southern equatorial stripe.
MATSUOKA Y., PETERSON B.A., MURATA K.L., FUJIWARA M., NAGAYAMA T., SUENAGA T., FURUSAWA K., MIYAKE N., OMORI K., SUZUKI D. and WADA K.
Abstract (from CDS):
We report the discovery of two field brown dwarfs, ULAS J0128-0041 and ULAS J0321+0051, and the rediscovery of ULAS J0226+0051 (IfA 0230-Z1), in the Sloan Digital Sky Survey (SDSS) southern equatorial stripe. They are found in the course of our follow-up observation program of 1 µm excess sources in the United Kingdom Infrared Telescope Infrared Deep Sky Survey. The Gemini Multi-Object Spectrographs spectra at red optical wavelengths (6500-10500 Å) are presented, which reveal that they are early-T dwarfs. The classification is also supported by their optical to near-infrared colors. It is noted that ULAS J0321+0051 is one of the faintest currently known T dwarfs. The estimated distances to the three objects are 50-110 pc, thus they are among the most distant field T dwarfs known. The dense temporal coverage of the target fields achieved by the SDSS-II Supernova Survey allows us to perform a simple time-series analysis of the dwarfs. We create stacked images of each year from 2002-2007 and find significant proper motions of 150-290 mas/yr or transverse velocities of 40-100 km/s for ULAS J0128-0041 and ULAS J0226+0051. We also find that there are no detectable, long-term (a-few-year) brightness variations above a few times 0.1 mag for the two brown dwarfs.
brown dwarfs - stars: individual (ULAS J0128-0041, ULAS J0226+0051, ULAS J0321+0051) - stars: low-mass - surveys
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