A Keck/HIRES Doppler Search for Planets Orbiting Metal-Poor Dwarfs

Abstract

We present results from our ongoing spectroscopic search for giant planets within 1 AU around a well-defined sample of metal-poor stars with HIRES on the Keck 1 telescope. We have achieved an rms radial velocity precision of $\sim 8$ m/s over a time-span of 1.5 years. The data collected so far build toward evidence of the absence of very short-period ($< 1$ month) giant planets. However, about 7% of the stars in our sample exhibits velocity trends indicative of the existence of companions. We place preliminary upper limits on the detectable companion mass as a function of orbital period, and compare them with the performance of ESA&#39;s future space-borne high-precision astrometric observatory Gaia.