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Five Planets Orbiting 55 Cancri

Fischer, Debra A. and Marcy, Geoffrey W. and Butler, R. Paul and Vogt, Steven S. and Laughlin, Greg and Henry, Gregory W. and Abouav, David and Peek, Kathryn M. G. and Wright, Jason T. and Johnson, John A. and McCarthy, Chris and Isaacson, Howard (2008) Five Planets Orbiting 55 Cancri. Astrophysical Journal, 675 (1). pp. 790-801. ISSN 0004-637X. doi:10.1086/525512.

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We report 18 years of Doppler shift measurements of a nearby star, 55 Cancri, that exhibits strong evidence for five orbiting planets. The four previously reported planets are strongly confirmed here. A fifth planet is presented, with an apparent orbital period of 260 days, placing it 0.78 AU from the star in the large empty zone between two other planets. The velocity wobble amplitude of 4.9 m s^(−1) implies a minimum planet mass Msin i = 45.7 M_⊕. The orbital eccentricity is consistent with a circular orbit, but modest eccentricity solutions give similar χ^2_ν fits. All five planets reside in low-eccentricity orbits, four having eccentricities under 0.1. The outermost planet orbits 5.8 AU from the star and has a minimum mass Msin i = 3.8 M_(Jup), making it more massive than the inner four planets combined. Its orbital distance is the largest for an exoplanet with a well-defined orbit. The innermost planet has a semimajor axis of only 0.038 AU and has a minimum mass, Msin i, of only 10.8 M_⊕, making it one of the lowest mass exoplanets known. The five known planets within 6 AU define a minimum-mass protoplanetary nebula to compare with the classical minimum-mass solar nebula. Numerical N-body simulations show this system of five planets to be dynamically stable and show that the planets with periods of 14.65 and 44.3 days are not in a mean motion resonance. Millimagnitude photometry during 11 years reveals no brightness variations at any of the radial velocity periods, providing support for their interpretation as planetary.

Item Type:Article
Related URLs:
URLURL TypeDescription
Fischer, Debra A.0000-0003-2221-0861
Marcy, Geoffrey W.0000-0002-2909-0113
Laughlin, Greg0000-0002-3253-2621
Henry, Gregory W.0000-0003-4155-8513
Wright, Jason T.0000-0001-6160-5888
Johnson, John A.0000-0001-9808-7172
Isaacson, Howard0000-0002-0531-1073
Additional Information:© 2008 American Astronomical Society. Received 2007 May 8; accepted 2007 October 24. 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. We gratefully acknowledge the efforts and dedication of the Lick and Keck Observatory staff. We thank Karl Stapelfeldt for helpful comments.We thank the anonymous referee for comments that improved the manuscript. We appreciate support by NASA grant NAG5-75005 and by NSF grant AST 03-07493 to S. S. V.; and support by NSF grant AST 99-88087, by NASA grant NAG5-12182, and travel support from the Carnegie Institution of Washington to R. P. B. G. W. H. acknowledges support from NASA grant NCC5-511 and NSF grant HRD-9706268. We are also grateful for support by Sun Microsystems. We thank the NASA and UC Telescope assignment committees for allocations of telescope time toward the planet search around M dwarfs. This research has made use of the SIMBAD database, operated at CDS, Strasbourg, France. The authors wish to extend special thanks to those of Hawaiian 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.
Funding AgencyGrant Number
NSFAST 03-07493
NSFAST 99-88087
Sun MicrosystemsUNSPECIFIED
Carnegie Institution of WashingtonUNSPECIFIED
Issue or Number:1
Record Number:CaltechAUTHORS:20130111-131548446
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Official Citation:Five Planets Orbiting 55 Cancri Debra A. Fischer et al. 2008 ApJ 675 790
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:36324
Deposited By: Ruth Sustaita
Deposited On:11 Jan 2013 21:38
Last Modified:09 Nov 2021 23:21

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