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MOA-2016-BLG-227Lb: A Massive Planet Characterized by Combining Light-curve Analysis and Keck AO Imaging

Koshimoto, N. and Gelino, C. R. and Beichman, C. and Calchi Novati, S. (2017) MOA-2016-BLG-227Lb: A Massive Planet Characterized by Combining Light-curve Analysis and Keck AO Imaging. Astronomical Journal, 154 (1). Art. No. 3. ISSN 1538-3881.

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We report the discovery of a microlensing planet—MOA-2016-BLG-227Lb—with a large planet/host mass ratio of q ≃ 9 × 10^(−3). This event was located near the K2 Campaign 9 field that was observed by a large number of telescopes. As a result, the event was in the microlensing survey area of a number of these telescopes, and this enabled good coverage of the planetary light-curve signal. High angular resolution adaptive optics images from the Keck telescope reveal excess flux at the position of the source above the flux of the source star, as indicated by the light-curve model. This excess flux could be due to the lens star, but it could also be due to a companion to the source or lens star, or even an unrelated star. We consider all these possibilities in a Bayesian analysis in the context of a standard Galactic model. Our analysis indicates that it is unlikely that a large fraction of the excess flux comes from the lens, unless solar-type stars are much more likely to host planets of this mass ratio than lower mass stars. We recommend that a method similar to the one developed in this paper be used for other events with high angular resolution follow-up observations when the follow-up observations are insufficient to measure the lens–source relative proper motion.

Item Type:Article
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URLURL TypeDescription Paper
Beichman, C.0000-0002-5627-5471
Calchi Novati, S.0000-0002-7669-1069
Additional Information:© 2017 The American Astronomical Society. Received 2017 April 6; revised 2017 May 4; accepted 2017 May 4; published 2017 June 9. Work by N.K. is supported by JSPS KAKENHI Grant Number JP15J01676. The MOA project is supported by grants JSPS25103508 and 23340064. D.P.B., A.B., and D.S. were supported by NASA through grants NNX13AF64G, NNX16AC71G, and NNX16AN59G. Work by Y.S. and C.B.H. was supported by an appointment to the NASA Postdoctoral Program at the Jet Propulsion Laboratory, California Institute of Technology, administered by Universities Space Research Association through a contract with NASA. N.J.R. is a Royal Society of New Zealand Rutherford Discovery Fellow. Work by A.F. is supported by JSPS KAKENHI grant No. JP17H02871. Work by C.R. was supported by an appointment to the NASA Postdoctoral Program at the Goddard Space Flight Center, administered by USRA through a contract with NASA. Work by S.C.N. was supported by NExScI. A.C. acknowledges financial support from Université Pierre et Marie Curie under grants Émergence@Sorbonne Universités 2016 and Émergence-UPMC 2012. This work was supported by a NASA Keck PI Data Award, administered by the NASA Exoplanet Science Institute. Data presented herein were obtained at the W. M. Keck Observatory from telescope time allocated to the National Aeronautics and Space Administration through the agency's scientific partnership with the California Institute of Technology and the University of California. The Observatory was made possible by the generous financial support of the W.M. Keck Foundation. The authors wish to recognize and acknowledge the very significant cultural role and reverence that the summit of Maunakea has always had within the indigenous Hawaiian community. We are most fortunate to have the opportunity to conduct observations from this mountain. The United Kingdom Infrared Telescope (UKIRT) is supported by NASA and operated under an agreement among the University of Hawaii, the University of Arizona, and Lockheed Martin Advanced Technology Center; operations are enabled through the cooperation of the Joint Astronomy Centre of the Science and Technology Facilities Council of the U.K. We acknowledge the support from NASA HQ for the UKIRT observations in connection with K2C9. This research uses data obtained through the Telescope Access Program (TAP), which has been funded by the National Astronomical Observatories of China, the Chinese Academy of Sciences (the Strategic Priority Research Program "The Emergence of Cosmological Structures" Grant No. XDB09000000), and the Special Fund for Astronomy from the Ministry of Finance. This work is partly based on observations obtained with MegaPrime/MegaCam, a joint project of CFHT and CEA/DAPNIA, at the Canada–France–Hawaii Telescope (CFHT), which is operated by the National Research Council (NRC) of Canada, the Institut National des Science de l'Univers of the Centre National de la Recherche Scientifique (CNRS) of France, and the University of Hawaii. This work was performed in part under contract with the California Institute of Technology (Caltech)/Jet Propulsion Laboratory (JPL) funded by NASA through the Sagan Fellowship Program executed by the NASA Exoplanet Science Institute. Work by M.T.P. and B.S.G. was supported by NASA grant NNX16AC62G. This work was partly supported by the National Science Foundation of China (grant No. 11333003, 11390372 to S.M.). Based on observations made with ESO Telescopes at the La Silla Paranal Observatory under programme ID 097.C-0261.
Group:Infrared Processing and Analysis Center (IPAC)
Funding AgencyGrant Number
Japan Society for the Promotion of Science (JSPS)JP15J01676
Japan Society for the Promotion of Science (JSPS)JSPS25103508
Japan Society for the Promotion of Science (JSPS)23340064
NASA Postdoctoral ProgramUNSPECIFIED
Royal Society of New ZealandUNSPECIFIED
Japan Society for the Promotion of Science (JSPS)JP17H02871
NASA Exoplanet Science Institute (NExScI)UNSPECIFIED
Université Pierre et Marie CurieÉmergence@Sorbonne Universités 2016
Université Pierre et Marie CurieÉmergence-UPMC 2012
W. M. Keck FoundationUNSPECIFIED
National Astronomical Observatories of ChinaUNSPECIFIED
Chinese Academy of SciencesXDB09000000
Ministry of Finance (China)UNSPECIFIED
National Natural Science Foundation of China11333003
National Natural Science Foundation of China11390372
Subject Keywords:gravitational lensing: micro – planetary systems
Issue or Number:1
Record Number:CaltechAUTHORS:20170612-110523802
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Official Citation:N. Koshimoto et al 2017 AJ 154 3
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:78104
Deposited By: Tony Diaz
Deposited On:12 Jun 2017 18:21
Last Modified:24 Feb 2020 10:30

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