Systematic Korea Microlensing Telescope Network planetary anomaly search – III. One wide-orbit planet and two stellar binaries

Creators: Wang, Hanyue; Zang, Weicheng; Zhu, Wei; Hwang, Kyu-Ha; Udalski, Andrzej; Gould, Andrew; Han, Cheongho; Albrow, Michael D.; Chung, Sun-Ju; Jung, Youn Kil; Kim, Doeon; Ryu, Yoon-Hyun; Shin, In-Gu; Shvartzvald, Yossi; Yee, Jennifer C.; Cha, Sang-Mok; Kim, Dong-Jin; Kim, Hyoun-Woo; Kim, Seung-Lee; Lee, Chung-Uk; Lee, Dong-Joo; Lee, Yongseok; Park, Byeong-Gon; Pogge, Richard W.; Poleski, Radoslaw; Mróz, Przemek; Skowron, Jan; Szymański, Michał K.; Soszyński, Igor; Pietrukowicz, Paweł; Kozłowski, Szymon; Ulaczyk, Krzysztof; Rybicki, Krzysztof A.; Iwanek, Patryk; Wrona, Marcin; Gromadzki, Mariusz; Yang, Hongjing; Mao, Shude; Zhang, Xiangyu; KMTNet Collaboration; OGLE Collaboration; Tsinghua Microlensing Group

Abstract

Only a few wide-orbit planets around old stars have been detected, which limits our statistical understanding of this planet population. Following the systematic search for planetary anomalies in microlensing events found by the Korea Microlensing Telescope Network, we present the discovery and analysis of three events that were initially thought to contain wide-orbit planets. The anomalous feature in the light curve of OGLE-2018-BLG-0383 is caused by a planet with mass ratio q = 2.1 × 10⁻⁴ and a projected separation s = 2.45. This makes it the lowest mass-ratio microlensing planet at such wide orbits. The other two events, KMT-2018-BLG-0998 and OGLE-2018-BLG-0271, are shown to be stellar binaries (q > 0.1) with rather close (s < 1) separations. We briefly discuss the properties of known wide-orbit microlensing planets and show that the survey observations are crucial in discovering and further statistically constraining such a planet population.

Additional Information

© 2021 The Author(s) Published by Oxford University Press on behalf of Royal Astronomical Society. This article is published and distributed under the terms of the Oxford University Press, Standard Journals Publication Model (https://academic.oup.com/journals/pages/open_access/funder_policies/chorus/standard_publication_model) Accepted 2021 December 1. Received 2021 November 29; in original form 2021 October 6. We acknowledge the science research grants from the China Manned Space Project with no. CMS-CSST-2021-A11. WZ, HY, SM, and XZ acknowledge support by the National Science Foundation of China (grant no. 11821303 and 11761131004). This research has made use of the KMTNet system operated by the Korea Astronomy and Space Science Institute and the data were obtained at three host sites of CTIO in Chile, SAAO in South Africa, and SSO in Australia. Work by JCY was supported by JPL grant 1571564. Work by CH was supported by the grants of National Research Foundation of Korea (2019R1A2C2085965 and 2020R1A4A2002885). Work by RP was supported by Polish National Agency for Academic Exchange grant 'Polish Returns 2019.' This research has made use of the NASA Exoplanet Archive, which is operated by the California Institute of Technology, under contract with the National Aeronautics and Space Administration under the Exoplanet Exploration Program. DATA AVAILABILITY. Data used in the light-curve analysis will be provided along with publication.

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