2013AJ....145..155D

We describe the discovery of a likely brown dwarf (BD) companion with a minimum mass of 31.7±2.0 M_Jup to GSC 03546-01452 from the MARVELS radial velocity survey, which we designate as MARVELS-6b. For reasonable priors, our analysis gives a probability of 72% that MARVELS-6b has a mass below the hydrogen-burning limit of 0.072 M_☉, and thus it is a high-confidence BD companion. It has a moderately long orbital period of 47.8929_–0.0062^+0.0063 days with a low eccentricity of 0.1442_–0.0073^+0.0078, and a semi-amplitude of 1644_–13⁺¹² m/s. Moderate resolution spectroscopy of the host star has determined the following parameters: T_eff= 5598±63, log g = 4.44±0.17, and [Fe/H] = +0.40 ±0.09. Based upon these measurements, GSC 03546-01452 has a probable mass and radius of M_*= 1.11±0.11 M_☉ and R_*= 1.06±0.23 R _☉ with an age consistent with less than ∼6 Gyr at a distance of 219±21 pc from the Sun. Although MARVELS-6b is not observed to transit, we cannot definitively rule out a transiting configuration based on our observations. There is a visual companion detected with Lucky Imaging at 7.''7 from the host star, but our analysis shows that it is not bound to this system. The minimum mass of MARVELS-6b exists at the minimum of the mass functions for both stars and planets, making this a rare object even compared to other BDs. It also exists in an underdense region in both period/eccentricity and metallicity/eccentricity space.