Six New Planets from the Keck Precision Velocity Survey

Abstract

We report results of a search for planets around 500 main sequence stars using the Keck high resolution spectrometer which has provided Doppler precision of 3 m/s during the past 3 yr. We report 6 new strong planet candidates having complete Keplerian orbits, with periods ranging from 24 d to 3 yr. We also provide updated orbital parameters for 4 previously announced planets. Four of the six newly discovered planets have minimum Msini masses less than 2 Mjup, while the remaining two have Msini $\sim$ 5 Mjup. The distribution of planetary masses continues to exhibit a rise toward lower masses. The orbital eccentricities of the new planets range from 0.12 to 0.71 which also continues the ubiquity of high eccentricities. All 18 known extrasolar planets orbiting beyond 0.2 AU have eccentricities greater than $\sim$0.1. The current limiting Doppler precision of the Keck Doppler survey is 3 m/s per observation as determined from observations of both stable stars and residuals to Keplerian fits.