A Second Planet Orbiting 47 Ursae Majoris

Abstract

Precise Doppler velocity measurements during 13 yr at Lick Observatory reveal the presence of two planets orbiting the star 47 UMa. The previously detected inner planet is conÐrmed by the newer veloci- ties that yield a revised orbital period Pb\1089.0^2.9 days, M sin i \2.54 and eccentricity eb\ 0.061^0.014. The residuals to that single-Keplerian Ðt exhibit a periodicity that is consistent with an MJ, additional planetary companion. A simultaneous Ðt for both planets implies that the outer planet has Pc\2594^90 days, a\3.73 AU, yet found for an extrasolar planet, and its angular separation from the host star of makes it a good 0\ec\0.2, and M sin i\0.76 MJ. Its semimajor axis is the largest 0A.26 target for direct detection and astrometry. Hipparcos astrometry places limits on the masses of these planets at less than D10 and dynamical modeling places limits on both and the orbital inclina- MJ, ec tions. The outer planet induces a velocity semiamplitude of K\11.1 m s~1 in the star during its 7 yr orbit, similar to the signal induced on the sun by Jupiter