A Search For Jupiter-Mass Companions To Near-By Stars

We have carefully monitored the radial velocities of 21 bright, solar-type stars for 12 years. None has shown any reflex motion due to a sub-stellar companion to an upper limit of between one and three Jupiter masses (\Thetasin i) for orbital periods less than 15 years. We can also rule out companions of more than 3 to 10 Jupiter masses (\Thetasin i) at much longer periods based on long-term trends in the radial velocities, limits imposed by astrometry and zones of orbital stability in wide binaries. When our negative result is combined with other searches, one can say that, so far, no planets of the order of a Jupiter-mass or greater ( 0.001 M fi ) have been detected in short-period, circular orbits around some 45 nearby, solar-type stars. This absence presents an interesting challenge to theories of planet formation. I. INTRODUCTION The unequivocal detection of planets revolving about other stars would not only have a philosophical impact but would also be a first step in answering..