Searches for Low-Mass Extrasolar Planets

Andrew Howard
UC Berkeley


The NASA-UC Eta-Earth Survey by the California Planet Search (CPS)  group is a systematic search for low-mass planets (~3-30 Earth masses)  orbiting the nearest 230 GKM stars suitable for high-precision Doppler  observations at Keck Observatory.  These 1 m/s radial velocity  measurements of a well-defined sample of nearby stars will provide one  the first estimates of the fraction of stars with Earth-like planets.   This talk will describe the Eta-Earth Survey and other searches for  low-mass planets.  It will focus on recently announced super-Earths  and Neptune-mass planets from the Eta-Earth Survey, including HD  7924b, a 9.3 Earth mass (Msini) planet in a 5.4 day orbit. These low- mass planets are extraordinarily valuable in their own right, as  targets for transit and other follow-up studies, and as windows into  the mechanisms of planet formation.