A Long-Period Jupiter-Mass Planet Orbiting the Nearby M Dwarf GJ 849

We report precise Doppler measurements of GJ 849 (M3.5 V) that reveal the presence of a planet with a minimum mass of 0.82MJup in a 5.16 yr orbit. At a=2.35 AU, GJ 849b is the first Doppler-detected planet discovered around an M dwarf orbiting beyond 0.21 AU, and is only the second Jupiter-mass planet discovered around a star less massive than 0.5 M_solar. This detection brings to four the number of M stars known to harbor planets. Based on the results of our survey of 1300 FGKM main-sequence stars we find that giant planets within 2.5 AU are ~3 times more common around GK stars than around M stars. Due to GJ 849's proximity of 8.8 pc, the planet's angular separation is 0.27", making this system a prime target for high-resolution imaging using adaptive optics and future space-borne missions such as the Space Interferometry Mission PlanetQuest. We also find evidence of a linear trend in the velocity time series, which may be indicative of an additional planetary companion.

Based on observations obtained at the W. M. Keck Observatory, which is operated jointly by the University of California and the California Institute of Technology. Keck time has been granted by both NASA and the University of California.