A SUBSTELLAR COMPANION IN A 1.3 yr NEARLY CIRCULAR ORBIT OF HD 16760

We report the detection of a substellar companion orbiting the G5 dwarf HD 16760 from the N2K sample. Precise Doppler measurements of the star from Subaru and Keck revealed a Keplerian velocity variation with a period of 466.47 +/- 0.35 d, a semiamplitude of 407.71 +/- 0.84 m s(-1), and an eccentricity of 0.084 +/- 0.003. Adopting a stellar mass of 0.78 +/- 0.05 M(circle dot), we obtain a minimum mass for the companion of 13.13 +/- 0.56 M(JUP), which is close to the planet/brown-dwarf transition, and the semimajor axis of 1.084 +/- 0.023 AU. The nearly circular orbit despite the large mass and intermediate orbital period makes this companion unique among known substellar companions.