Johnson, John Asher and Howard, Andrew W. and Marcy, Geoffrey W. and Bowler, Brendan P. and Henry, Gregory W. and Fischer, Debra A. and Apps, Kevin and Isaacson, Howard and Wright, Jason T. (2010) The California Planet Survey. II. A Saturn-Mass Planet Orbiting the M Dwarf Gl 649. Publications of the Astronomical Society of the Pacific, 122 (888). pp. 149-155. ISSN 0004-6280 http://resolver.caltech.edu/CaltechAUTHORS:20100304-100031836
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We report precise Doppler measurements of the nearby (d = 10.34 pc) M dwarf Gl 649 that reveal the presence of a planet with a minimum mass M_P sin i = 0.328 M_(Jup) in an eccentric (e = 0.30), 598.3 day orbit. Our photometric monitoring reveals Gl 649 to be a new variable star with brightness changes on both rotational and decadal timescales. However, neither of these timescales are consistent with the 600 day Doppler signal and so provide strong support for planetary reflex motion as the best interpretation of the observed radial velocity variations. Gl 649b is only the seventh Doppler-detected giant planet around an M dwarf. The properties of the planet and host-star therefore contribute significant information to our knowledge of planet formation around low-mass stars. We revise and refine the occurrence rate of giant planets around M dwarfs based on the California Planet Survey sample of low-mass stars (M_* < 0.6 M_☉). We find that f = 3.4^(+2.2%)_(-0.9%) of stars with M_* < 0.6 M☉ harbor planets with M_P sin i > 0.3 M_(Jup) and a < 2.5 AU. When we restrict our analysis to metal-rich stars with [Fe/H] > +0.2, we find that the occurrence rate is 10.7^(+5.9%)_(-4.2%).
|Additional Information:||© 2010 Astronomical Society of the Pacific. Received 2009 November 7; accepted 2009 December 17; published 2010 January 26. We thank the many observers who contributed to the velocities reported here. We gratefully acknowledge the efforts and dedication of the Keck Observatory staff, especially Grant Hill and Scott Dahm for support of HIRES and Greg Wirth for support of remote observing. We are also grateful to the time assignment committees of NASA, NOAO, and the University of California for their generous allocations of observing time. We acknowledge R. Paul Butler and S. S. Vogt for many years of contributing to the data presented here. A. W. H. gratefully acknowledges support from a Townes Postdoctoral Fellowship at the University of California, Berkeley Space Sciences Laboratory. J. A. J. thanks the NSF Astronomy and Astrophysics Postdoctoral Fellowship program for support in the years leading to the completion of this work, and acknowledges support from NSF grant AST-0702821. G. W. M. acknowledges NASA grant NNX06AH52G. J. T.W. received support from NSF grant AST-0504874. G. W. H. acknowledges support from NASA, NSF, Tennessee State University, and the State of Tennessee through its Centers of Excellence program. Finally, we wish to extend special thanks to those of Hawai‘ian ancestry on whose sacred mountain of Mauna Kea we are privileged to be guests. Without their generous hospitality, the Keck observations presented herein would not have been possible.|
|Official Citation:||The California Planet Survey. II. A Saturn-Mass Planet Orbiting the M Dwarf Gl 649 John Asher Johnson, Andrew W. Howard, Geoffrey W. Marcy, Brendan P. Bowler, Gregory W. Henry, Debra A. Fischer, Kevin Apps, Howard Isaacson, and Jason T. Wright Publications of the Astronomical Society of the Pacific 2010 122:888, 149-155|
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|Deposited By:||Jason Perez|
|Deposited On:||12 Mar 2010 17:40|
|Last Modified:||26 Dec 2012 11:49|
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