Five New Extrasolar Planets

Abstract

We report multiple Doppler measurements of five nearby FGK main sequence stars and subgiants obtained during the past 4-6 years at the Keck observa- tory. These stars, namely, HD 183263, HD 117207, HD 188015, HD 45350, and HD 99492 all exhibit coherent variations in their Doppler shifts consistent with a planet in Keplerian motion. The five new planets occupy known realms of planetary parameter space, including a wide range of orbital eccentricities, e=0- 0.78, and semimajor axes, 0.1-3.8 AU that provide further statistical information about the true distributions of various properties of planetary systems. One of the planets, HD 99492b, has a low minimum mass of 0.112 MJUP =3 6 M Earth. Four of the five planets orbit beyond 1 AU. We describe two quantitative tests of the false alarm probability for Keplerian interpretations of measured veloci- ties. The more robust of these involves Monte-Carlo realizations of scrambled velocities as a proxy for noise. Keplerian orbital fits to that "noise" yield the distribution of χ2 ν to compare with χ2 ν from the original (unscrambled) velocities.