The Discovery of a Second Field Methane Brown Dwarf from Sloan Digital Sky Survey Commissioning Data.
We report the discovery of a second field methane brown dwarf from the commissioning data of the Sloan Digital Sky Survey (SDSS). The object, SDSS J134646.45-003150.4 (hereafter SDSS 1346-00), was selected because of its very red color and stellar appearance. Its spectrum between 0.8 and 2.5 µm is dominated by strong absorption bands of H2O and CH4 and closely mimics those of Gliese 229B and SDSS 162414.37+002915.6 (hereafter SDSS 1624+00), two other known methane brown dwarfs. SDSS 1346-00 is approximately 1.5 mag fainter than Gliese 229B, suggesting that it lies about 11 pc from the Sun. The ratio of flux at 2.1 µm to that at 1.27 µm is larger for SDSS 1346-00 than for Gliese 229B and SDSS 1624+00, which suggests that SDSS 1346-00 has a slightly higher effective temperature than the others. Based on a search area of 130 deg2 and a detection limit of z*=19.8, we estimate a space density of 0.05 pc-3 for methane brown dwarfs with Teff approximately 1000 K in the 40 pc3 volume of our search. This estimate is based on small-sample statistics and should be treated with appropriate caution.
Tsvetanov
ZI
Golimowski
DA
Zheng
W
Geballe
TR
Leggett
SK
Ford
HC
Davidsen
AF
Uomoto
A
Fan
X
Knapp
GR
Strauss
MA
Brinkmann
J
Lamb
DQ
Newberg
HJ
Rechenmacher
R
Schneider
DP
York
DG
Lupton
RH
Pier
JR
Annis
J
Csabai
I
Hindsley
RB
Ivesic
Z
Munn
JA
Thakar
AR
Waddell
P