Two Exoplanets Discovered at Keck Observatory

We present two exoplanets detected at Keck Observatory. HD 179079 is a G5 subgiant that hosts a hot Neptune planet with M sin i = 27.5 M⊕ in a 14.48 d, low-eccentricity orbit. The stellar reflex velocity induced by this planet has a semiamplitude of K = 6.6 m s. HD 73534 is a G5 subgiant with a Jupiter-like planet of M sin i = 1.1 MJup and K = 16 m s −1 in a nearly circular 4.85 yr orbit. Both stars are chromospherically inactive and metal-rich. We discuss a known, classical bias in measuring eccentricities for orbits with velocity semiamplitudes, K, comparable to the radial velocity uncertainties. For exoplanets with periods longer than 10 days, the observed exoplanet eccentricity distribution is nearly flat for large amplitude systems (K > 80 m s), but rises linearly toward low eccentricity for lower amplitude systems (K > 20 m s). Subject headings: planetary systems — stars: individual (HD 179079, HD 73534, HD 143174) Based on observations obtained at the Keck Observatory, which is operated by the University of California Space Telescope Science Institute, 3700 San Martin Dr., Baltimore, MD 21218 Department of Physics & Astronomy, San Francisco State University, San Francisco, CA 94132 Department of Astronomy, University of California, Berkeley, Berkeley, CA Institute for Astronomy, University of Hawaii, Honolulu, HI 96822 Center of Excellence in Information Systems, Tennessee State University, 3500 John A. Merritt Boulevard, Box 9501, Nashville, TN 37209 Department of Astronomy, 226 Space Sciences Building, Cornell University, Ithaca, NY 14853