Twenty Years of Precise Radial Velocities at Keck and Lick Observatories

Twenty Years of Precise Radial Velocities at Keck and Lick Observatories

Authors:

Wright et al

Abstract:

The precise radial velocity survey at Keck Observatory began over 20 years ago. Its survey of thousands of stars now has the time baseline to be sensitive to planets with decade-long orbits, including Jupiter analogs. I present several newly-finished orbital solutions for long-period giant planets. Although hot Jupiters are generally "lonely" (i.e. they are not part of multiplanet systems), those that are not appear to often have giant companions at 5 AU or beyond. I present two of the highest period- ratios among planets in a two-planet system, and some of the longest orbital periods ever measured for exoplanets. In many cases, combining Keck radial velocities from those from other long-term surveys at Lick Observatory, McDonald Observatory, HARPS, and, of course, OHP spectrographs, produces superior orbital fits, constraining both period and eccentricity better than could be possible with any single set alone. Stellar magnetic activity cycles can masquerade as long-period planets. In most cases this effect is very small, but a loud minority of stars, including, apparently, HD 154345, show very strong RV-activity correlations.