VERY-LOW-MASS STELLAR AND SUBSTELLAR COMPANIONS TO SOLAR-LIKE STARS FROM MARVELS. III. A SHORT-PERIOD BROWN DWARF CANDIDATE AROUND AN ACTIVE G0IV SUBGIANT

We present an eccentric, short-period brown dwarf candidate orbiting the active, slightly evolved subgiant star TYC 2087-00255-1, which has effective temperature T sub(eff) = 5903 + or - 42 K, surface gravity log(g) = 4.07 + or - 0.16 (cgs), and metallicity [Fe/H] = -0.23 + or - 0.07. From our 38 radial velocity measurements spread over a two-year time baseline, we derive a Keplerian orbital fit with semi-amplitude K = 3.571 + or - 0.041 km s super(-1), period P= 9.0090 + or - 0.0004 days, and eccentricity e = 0.226 + or - 0.011. Through adaptive optics imaging we also found a point source 643 + or - 10 mas away from TYC 2087-00255-1, which would have a mass of 0.13 M sub([middot in circle]) if it is physically associated with TYC 2087-00255-1 and has the same age.