Ten New and Updated Multiplanet Systems and a Survey of Exoplanetary Systems

Creators: Wright, J. T.; Upadhyay, S.; Marcy, G. W.; Fischer, D. A.; Ford, Eric B.; Johnson, John Asher

Abstract

We present the latest velocities for ten multiplanet systems, including a re-analysis of archival Keck and Lick data, resulting in improved velocities that supersede our previously published measurements. We derive updated orbital fits for 10 Lick and Keck systems, including two systems (HD 11964, HD 183263) for which we provide confirmation of second planets only tentatively identified elsewhere, and two others (HD 187123 and HD 217107) for which we provide a major revision of the outer planet's orbit. We compile orbital elements from the literature to generate a catalog of the 28 published multiple-planet systems around stars within 200 pc. From this catalog we find several intriguing patterns emerging: (1) including those systems with long-term radial velocity trends, at least 28% of known planetary systems appear to contain multiple planets; (2) planets in multiple-planet systems have somewhat smaller eccentricities than single planets; and (3) the distribution of orbital distances of planets in multiplanet systems and single planets are inconsistent: single-planet systems show a pileup at P ~ 3 days and a jump near 1 AU, while multiplanet systems show a more uniform distribution in log-period. In addition, among all planetary systems we find the following. (1) There may be an emerging, positive correlation between stellar mass and giant-planet semimajor axis. (2) Exoplanets with M sin i > 1 M_(Jup) more massive than Jupiter have eccentricities broadly distributed across 0 < e < 0.5, while lower mass exoplanets exhibit a distribution peaked near e = 0.

Additional Information

© 2009 American Astronomical Society. Received 2008 August 16; accepted 2008 October 30; published 2009 March 5. The authors acknowledge and thank R. Paul Butler and Steven S. Vogt for their major contributions in obtaining the radial velocity measurements herein, without which this work would not have been possible. The authors also wish to acknowledge helpful discussions with many astronomers for providing and refining many of the ideas of this paper. An incomplete list would include Alan Boss, Eric Agol, Kristen Menou, James Kasting, Rory Barnes, and Ed Thommes. The work herein is 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. The Keck Observatory was made possible by the generous financial support of the W.M. Keck Foundation. We wish to recognize and acknowledge the very significant cultural role and reverence that the summit of Mauna Kea has always had within the indigenous Hawaiian community. We are most fortunate to have the opportunity to conduct observations from this mountain. This research has made use of the SIMBAD database, operated at CDS, Strasbourg, France, and of NASA's Astrophysics Data System Bibliographic Services, and is made possible by the generous support of NASA and the NSF, including grant AST-0307493. J.T.W received support from NSF grant AST-0504874. G.W.M. received support from NASA grant NNG06AH52G, and D.A.F from NASA grant NNG05G164G and the Cottrell Science Scholar Program. E.B.F acknowledges the support of NASA RSA 1326409. J.A.J is supported by NSF grant AST-0702821. The authors acknowledge the University of Florida High-Performance Computing Center for providing computational resources and support that have contributed to the results reported in this paper.

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