  We present an analysis of a new, detached, double-lined eclipsing binary
system with K7 Ve components, discovered as part of the University of New South
Wales Extrasolar Planet Search. The object is significant in that only 6 other
binary systems are known with comparable or lower mass. Such systems offer
important tests of mass-radius theoretical models. Follow-up photometry and
spectroscopy were obtained with the 40-inch and 2.3m telescopes at SSO
respectively. An estimate of the radial velocity amplitude from spectral
absorption features, combined with the orbital inclination (83.5 deg) estimated
from lightcurve fitting, yielded a total mass of M=(1.041 +/- 0.06)M_sun and
component masses of M_A=(0.529 +/- 0.035)M_sun and M_B=(0.512 +/- 0.035)M_sun.
The radial velocity amplitude estimated from absorption features (167 +/-
3)kmps was found to be less than the estimate from the H_alpha emission lines
(175 +/- 1.5)kmps. The lightcurve fit produced radii of R_A=(0.641 +/-
0.05)R_sun and R_B=(0.608 +/- 0.06)R_sun, and a temperature ratio of
T_B/T_A=0.980 +/- 0.015. The apparent magnitude of the binary was estimated to
be V=13.9 +/- 0.2. Combined with the spectral type, this gave the distance to
the binary as 169 +/- 14 pc. The timing of the secondary eclipse gave a lower
limit on the eccentricity of the binary system of 0.0025 +/- 0.0005. This is
the most statistically significant non-zero eccentricity found for such a
system, possibly suggesting the presence of a third companion.
