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OGLE-2016-BLG-1227L: A Wide-separation Planet from a Very Short-timescale Microlensing Event

Han, Cheongho and Udalski, Andrzej and Gould, Andrew and Albrow, Michael D. and Chung, Sun-Ju and Hwang, Kyu-Ha and Jung, Youn Kil and Lee, Chung-Uk and Ryu, Yoon-Hyun and Shin, In-Gu and Shvartzvald, Yossi and Yee, Jennifer C. and Zang, Weicheng and Cha, Sang-Mok and Kim, Dong-Jin and Kim, Hyoun-Woo and Kim, Seung-Lee and Lee, Dong-Joo and Lee, Yongseok and Park, Byeong-Gon and Pogge, Richard W. and Jee, M. James and Kim, Doeon and Kim, Chun-Hwey and Kim, Woong-Tae and Mróz, Przemek and Szymański, Michał K. and Skowron, Jan and Poleski, Radek and Soszyński, Igor and Pietrukowicz, Paweł and Kozlowski, Szymon and Ulaczyk, Krzysztof (2020) OGLE-2016-BLG-1227L: A Wide-separation Planet from a Very Short-timescale Microlensing Event. Astronomical Journal, 159 (3). Art. No. 91. ISSN 1538-3881.

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We present the analysis of the microlensing event OGLE-2016-BLG-1227. The light curve of this short-duration event appears to be a single-lens event affected by severe finite-source effects. Analysis of the light curve based on single-lens single-source (1L1S) modeling yields very small values of the event timescale, t_E ∼ 3.5 days, and the angular Einstein radius, θ_E ∼ 0.009 mas, making the lens a candidate of a free-floating planet. Close inspection reveals that the 1L1S solution leaves small residuals with amplitude ΔI ≲ 0.03 mag. We find that the residuals are explained by the existence of an additional widely-separated heavier lens component, indicating that the lens is a wide-separation planetary system rather than a free-floating planet. From Bayesian analysis, it is estimated that the planet has a mass of _p = 0.79^(+1.30)_(−0.39) M_J and it is orbiting a low-mass host star with a mass of M_(host) = 0.10+0.17−0.05 M_⊙ located with a projected separation of a_ = 3.4^(+2.1)_(−1.0) au. The planetary system is located in the Galactic bulge with a line-of-sight separation from the source star of D_(LS) = 1.21^(+0.96)_(−0.63) kpc. The event shows that there are a range of deviations in the signatures of host stars for apparently isolated planetary lensing events and that it is possible to identify a host even when a deviation is subtle.

Item Type:Article
Related URLs:
URLURL TypeDescription Paper
Han, Cheongho0000-0002-2641-9964
Udalski, Andrzej0000-0001-5207-5619
Albrow, Michael D.0000-0003-3316-4012
Chung, Sun-Ju0000-0001-6285-4528
Hwang, Kyu-Ha0000-0002-9241-4117
Jung, Youn Kil0000-0002-0314-6000
Ryu, Yoon-Hyun0000-0001-9823-2907
Shin, In-Gu0000-0002-4355-9838
Shvartzvald, Yossi0000-0003-1525-5041
Yee, Jennifer C.0000-0001-9481-7123
Zang, Weicheng0000-0001-6000-3463
Kim, Hyoun-Woo0000-0001-8263-1006
Pogge, Richard W.0000-0003-1435-3053
Kim, Chun-Hwey0000-0001-8591-4562
Kim, Woong-Tae0000-0003-4625-229X
Mróz, Przemek0000-0001-7016-1692
Skowron, Jan0000-0002-2335-1730
Poleski, Radek0000-0002-9245-6368
Soszyński, Igor0000-0002-7777-0842
Pietrukowicz, Paweł0000-0002-2339-5899
Ulaczyk, Krzysztof0000-0001-6364-408X
Additional Information:© 2020. The American Astronomical Society. Received 2019 November 26; revised 2020 January 8; accepted 2020 January 9; published 2020 February 6. Work by C.H. was supported by the grants of National Research Foundation of Korea (2017R1A4A1015178 and 2019R1A2C2085965). Work by A.G. was supported by US NSF grant AST-1516842 and by JPL grant 1500811. A.G. received support from the European Research Council under the European Union's Seventh Framework Programme (FP 7) ERC Grant Agreement No. [32103]. The OGLE project has received funding from the National Science Centre, Poland, grant MAESTRO 2014/14/A/ST9/00121 to A.U. This research has made use of the KMTNet system operated by the Korea Astronomy and Space Science Institute (KASI) and the data were obtained at three host sites of CTIO in Chile, SAAO in South Africa, and SSO in Australia. Work by R.P. was partly supported by Polish National Agency for Academic Exchange grant Polish Returns 2019. We acknowledge the high-speed internet service (KREONET) provided by Korea Institute of Science and Technology Information (KISTI).
Funding AgencyGrant Number
National Research Foundation of Korea2017R1A4A1015178
National Research Foundation of Korea2019R1A2C2085965
European Research Council (ERC)32103
National Science Centre (Poland)2014/14/A/ST9/00121
Polish National Agency for Academic ExchangeUNSPECIFIED
Subject Keywords:Gravitational lensing ; Gravitational microlensing exoplanet detection
Issue or Number:3
Classification Code:Unified Astronomy Thesaurus concepts: Gravitational lensing (670); Gravitational microlensing exoplanet detection (2147)
Record Number:CaltechAUTHORS:20200206-125056439
Persistent URL:
Official Citation:Cheongho Han et al 2020 AJ 159 91
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:101163
Deposited By: George Porter
Deposited On:07 Feb 2020 19:01
Last Modified:07 Feb 2020 19:01

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