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

N. Koshimoto, Y. Shvartzvald, D. P. Bennett, M. T. Penny, M. Hundertmark, I. A. Bond, W. C. Zang, C. B. Henderson, D. Suzuki, N. J. Rattenbury, T. Sumi, F. Abe, Y. Asakura, A. Bhattacharya, M. Donachie, P. Evans, A. Fukui, Y. Hirao, Y. Itow, M. C.A. LiC. H. Ling, K. Masuda, Y. Matsubara, T. Matsuo, Y. Muraki, M. Nagakane, K. Ohnishi, C. Ranc, To Saito, A. Sharan, H. Shibai, D. J. Sullivan, P. J. Tristram, T. Yamada, T. Yamada, A. Yonehara, C. R. Gelino, C. Beichman, J. P. Beaulieu, J. B. Marquette, V. Batista, M. Friedmann, N. Hallakoun, S. Kaspi, D. Maoz, G. Bryden, S. Calchi Novati, S. B. Howell, T. S. Wang, S. Mao, P. Fouqué, H. Korhonen, U. G. Jørgensen, R. Street, Y. Tsapras, M. Dominik, E. Kerins, A. Cassan, C. Snodgrass, E. Bachelet, V. Bozza, D. M. Bramich

Research output: Contribution to journalArticlepeer-review

Abstract

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.

Original languageEnglish
Article number3
JournalAstronomical Journal
Volume154
Issue number1
DOIs
StatePublished - Jul 2017

Funding

FundersFunder number
National Aeronautics and Space AdministrationNNX16AC62G
Science and Technology Facilities CouncilST/P000649/1, ST/L004569/1
Japan Society for the Promotion of Science17H02871, 16H05732, 15J01676, 16H06287, 17J02146
National Natural Science Foundation of China097.C-0261, 11333003, 11390372

    Keywords

    • gravitational lensing: micro
    • planetary systems

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