THE NASA-UC ETA-EARTH PROGRAM. III. A SUPER-EARTH ORBITING HD 97658 AND A NEPTUNE-MASS PLANET ORBITING Gl 785*

摘要

We report the discovery of planets orbiting two bright, nearby early K dwarf stars, HD?97658 and Gl?785. These planets were detected by Keplerian modeling of radial velocities measured with Keck-HIRES for the NASA-UC Eta-Earth Survey. HD?97658?b is a close-in super-Earth with minimum mass Msin i = 8.2 ± 1.2?M ⊕, orbital period P = 9.494 ± 0.005?days, and an orbit that is consistent with circular. Gl?785?b is a Neptune-mass planet with Msin i = 21.6 ± 2.0?M ⊕, P = 74.39 ± 0.12?days, and orbital eccentricity e = 0.30 ± 0.09. Photometric observations with the T12 0.8?m automatic photometric telescope at Fairborn Observatory show that HD?97658 is photometrically constant at the radial velocity period to 0.09?mmag, supporting the existence of the planet.