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Statistics of Long Period Gas Giant Planets in Known Planetary Systems

Bryan, Marta L. and Knutson, Heather A. and Howard, Andrew W. and Ngo, Henry and Batygin, Konstantin and Crepp, Justin R. and Fulton, B. J. and Hinkley, Sasha and Isaacson, Howard and Johnson, John A. and Marcy, Geoffry W. and Wright, Jason T. (2016) Statistics of Long Period Gas Giant Planets in Known Planetary Systems. Astrophysical Journal, 821 (2). Art. No. 89. ISSN 0004-637X.

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We conducted a Doppler survey at Keck combined with NIRC2 K-band adaptive optics (AO) imaging to search for massive, long-period companions to 123 known exoplanet systems with one or two planets detected using the radial velocity (RV) method. Our survey is sensitive to Jupiter-mass planets out to 20 au for a majority of stars in our sample, and we report the discovery of eight new long-period planets, in addition to 20 systems with statistically significant RV trends that indicate the presence of an outer companion beyond 5 au. We combine our RV observations with AO imaging to determine the range of allowed masses and orbital separations for these companions, and account for variations in our sensitivity to companions among stars in our sample. We estimate the total occurrence rate of companions in our sample to be 52 ± 5% over the range 1–20 M_(Jup) and 5–20 au. Our data also suggest a declining frequency for gas giant planets in these systems beyond 3–10 au, in contrast to earlier studies that found a rising frequency for giant planets in the range 0.01–3 au. This suggests either that the frequency of gas giant planets peaks between 3 and 10 au, or that outer companions in these systems have a different semi-major axis distribution than the overall population of gas giant planets. Our results also suggest that hot gas giants may be more likely to have an outer companion than cold gas giants. We find that planets with an outer companion have higher average eccentricities than their single counterparts, suggesting that dynamical interactions between planets may play an important role in these systems.

Item Type:Article
Related URLs:
URLURL TypeDescription Paper
Bryan, Marta L.0000-0002-6076-5967
Knutson, Heather A.0000-0002-0822-3095
Howard, Andrew W.0000-0001-8638-0320
Ngo, Henry0000-0001-5172-4859
Batygin, Konstantin0000-0002-7094-7908
Crepp, Justin R.0000-0003-0800-0593
Fulton, B. J.0000-0003-3504-5316
Hinkley, Sasha0000-0001-8074-2562
Isaacson, Howard0000-0002-0531-1073
Johnson, John A.0000-0001-9808-7172
Marcy, Geoffry W.0000-0002-2909-0113
Wright, Jason T.0000-0001-6160-5888
Additional Information:© 2016 The American Astronomical Society. Received 2015 June 15; accepted 2016 January 22; published 2016 April 14. We thank David Hogg and Ben Montet for helpful conversations. This work was supported by NASA grant NNX14AD24G, and was based on observations at the W. M. Keck Observatory granted by the University of Hawaii, the University of California, the California Institute of Technology, Yale University, and NASA. We thank the observers who contributed to the measurements reported here and acknowledge the efforts of the Keck Observatory staff. We extend special thanks to those of Hawaiian ancestry on whose sacred mountain of Mauna Kea we are privileged to be guests.
Funding AgencyGrant Number
Subject Keywords:planetary systems; methods: statistical; techniques: radial velocities
Issue or Number:2
Record Number:CaltechAUTHORS:20160201-200104533
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Official Citation:Marta L. Bryan et al 2016 ApJ 821 89
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:64143
Deposited By: Joy Painter
Deposited On:03 Feb 2016 00:26
Last Modified:09 Mar 2020 13:18

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