1 {mu}m EXCESS SOURCES IN THE UKIDSS. I. THREE T DWARFS IN THE SLOAN DIGITAL SKY SURVEY SOUTHERN EQUATORIAL STRIPE
- Graduate School of Science, Nagoya University, Furo-cho, Chikusa-ku, Nagoya 464-8602 (Japan)
- Mount Stromlo Observatory, Research School of Astronomy and Astrophysics, Australian National University, Weston Creek P.O., ACT 2611 (Australia)
- Department of Astronomical Sciences, Graduate University for Advanced Studies (Sokendai), 2-21-1 Osawa, Mitaka, Tokyo 181-8588 (Japan)
- Solar-Terrestrial Environment Laboratory, Nagoya University, Nagoya 464-8601 (Japan)
- Department of Earth and Space Science, Osaka University, Osaka 560-0043 (Japan)
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 {mu}m excess sources in the United Kingdom Infrared Telescope Infrared Deep Sky Survey. The Gemini Multi-Object Spectrographs spectra at red optical wavelengths (6500-10500 A) 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{sup -1} or transverse velocities of 40-100 km s{sup -1} 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.
- OSTI ID:
- 21583004
- Journal Information:
- Astronomical Journal (New York, N.Y. Online), Vol. 142, Issue 2; Other Information: DOI: 10.1088/0004-6256/142/2/64; ISSN 1538-3881
- Country of Publication:
- United States
- Language:
- English
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