The Detection of a Large‐mass Planet Around a K0 IV Subgiant With an Almost‐circular Orbit

We report the detection of a new large‐mass planet orbiting around a K0 IV(V = 8.26) star which has a minimum mass M_p sin i = 10.70 ± 0.50 M_(Jup) in a 696.0 ± 2.6‐day orbit. It was detected in precise radial velocity (RV) measurements from Subaru and Keck. The derived orbital parameters, based on a χ^2 which minimized by Downhill Simplex algorithm, suggests that these radial velocity variations are consistent with an almost circular planetary orbit and a Mars‐like semimajor axis (e ∼ 0.0, a  =  1.70 ± 0.03 AU). Extra‐solar planets that have several times the mass of Jupiter orbiting in periods of hundreds or thousands of days, with very low eccentricities( e< 0.1), are rare discoveries. Our detection presents a new sample of these circular orbit massive planets.