During a survey for stars with disks in the Taurus star-forming region using the Spitzer Space Telescope , we have discovered a pair of young brown dwarfs , FU Tau A and B , in the Barnard 215 dark cloud .
They have a projected angular separation of 5.7 \arcsec , corresponding to 800 AU at the distance of Taurus .
To assess the nature of these two objects , we have obtained spectra of them and have constructed their spectral energy distributions .
Both sources are young ( \sim 1 Myr ) according to their H \alpha emission , gravity-sensitive spectral features , and mid-IR excess emission .
The proper motion of FU Tau A provides additional evidence of its membership in Taurus .
We measure spectral types of M7.25 and M9.25 for FU Tau A and B , respectively , which correspond to masses of \sim 0.05 and \sim 0.015 M _ { \odot } according to the evolutionary models of Chabrier and Baraffe .
FU Tau A is significantly overluminous relative to an isochrone passing through FU Tau B and relative to other members of Taurus near its spectral type , which may indicate that it is an unresolved binary .
FU Tau A and B are likely to be components of a binary system based on the low probability ( \sim 3 \times 10 ^ { -4 } ) that Taurus would produce two unrelated brown dwarfs with a projected separation of a \leq 6 \arcsec .
Barnard 215 contains only one other young star and is in a remote area of Taurus , making FU Tau A and B the first spectroscopically-confirmed brown dwarfs discovered forming in isolation rather than in a stellar cluster or aggregate .
Because they were born in isolation and comprise a weakly bound binary , dynamical interactions with stars could not have played a role in their formation , and thus are not essential for the birth of brown dwarfs .

ERRATUM : The K -band magnitude for FU Tau B in Table 1 is incorrect and should be 13.33 .
The bolometric luminosity of FU Tau B in Table 3 and Figure 5 is incorrect because of that mistake and a separate arithmetic error .
The correct value of the luminosity is 0.0039 L _ { \odot } .
FU Tau A and B exhibited different isochronal ages in the original Hertzsprung-Russell diagram in Figure 5 , which was unexpected for members of a binary system .
This discrepancy is reduced in the corrected version of Figure 5 since both objects are now above the isochrone for 1 Myr .
Given the large uncertainties in model isochrones at such young ages , the positions of FU Tau A and B in Figure 5 could be roughly consistent with coevality .