A Second Planet Orbiting 47 Ursae Majoris

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 days, M sin i \\ 2. 54 and eccentricityP b \\ 1089. 0 ^ 2. 9 MJ, eb\\0. 061 ^ 0. 014. The residuals to that single-Keplerian Ðt exhibit a periodicity that is consistent with an additional planetary companion. A simultaneous Ðt for both planets implies that the outer planet has days, a \\ 3. 73 AU, and M sin i \\ 0. 76 Its semimajor axis is the largestP c \\ 2594 ^ 90 0 \\ e c \\ 0. 2, MJ. yet found for an extrasolar planet, and its angular separation from the host star of makes it a good0A. 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, ections. 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. Subject headings: planetary systems È stars: individual (47 Ursae Majoris) 1.