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KMT-2018-BLG-1025Lb: microlensing super-Earth planet orbiting a low-mass star

Han, Cheongho and Udalski, Andrzej and Lee, Chung-Uk and Albrow, Michael D. and Chung, Sun-Ju and Gould, Andrew and Hwang, Kyu-Ha and Jung, Youn Kil and Kim, Doeon and Kim, Hyoun-Woo 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, Seung-Lee and Lee, Dong-Joo and Lee, Yongseok and Park, Byeong-Gon and Pogge, Richard W. and Kim, Chun-Hwey and Kim, Woong-Tae and Mróz, Przemek and Szymański, Michał K. and Skowron, Jan and Poleski, Radosław and Soszyński, Igor and Pietrukowicz, Paweł and Kozłowski, Szymon and Ulaczyk, Krzysztof and Rybicki, Krzysztof A. and Iwanek, Patryk and Wrona, Marcin (2021) KMT-2018-BLG-1025Lb: microlensing super-Earth planet orbiting a low-mass star. Astronomy and Astrophysics, 649 . Art. No. A90. ISSN 0004-6361.

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Aims. We aim to find missing microlensing planets hidden in the unanalyzed lensing events of previous survey data. Methods. For this purpose, we conducted a systematic inspection of high-magnification microlensing events, with peak magnifications of A_(peak) ≳ 30, in the data collected from high-cadence surveys in and before the 2018 season. From this investigation, we identified an anomaly in the lensing light curve of the event KMT-2018-BLG-1025. The analysis of the light curve indicates that the anomaly is caused by a very low mass-ratio companion to the lens. Results. We identify three degenerate solutions, in which the ambiguity between a pair of solutions (solutions B) is caused by the previously known close–wide degeneracy, and the degeneracy between these and the other solution (solution A) is a new type that has not been reported before. The estimated mass ratio between the planet and host is q ~ 0.8 × 10⁻⁴ for solution A and q ~ 1.6 × 10⁻⁴ for solutions B. From the Bayesian analysis conducted with measured observables, we estimate that the masses of the planet and host and the distance to the lens are (M_p, M_h, D_L) ~ (6.1 M_⊕, 0.22 M_⊙, 6.7 kpc) for solution A and ~(4.4 M_⊕, 0.08 M_⊙, 7.5 kpc) for solutions B. The planet mass is in the category of a super-Earth regardless of the solutions, making the planet the eleventh super-Earth planet, with masses lying between those of Earth and the Solar System’s ice giants, which were discovered by microlensing.

Item Type:Article
Related URLs:
URLURL TypeDescription Paper
Han, Cheongho0000-0002-2641-9964
Udalski, Andrzej0000-0001-5207-5619
Lee, Chung-Uk0000-0003-0043-3925
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
Kim, Hyoun-Woo0000-0001-8263-1006
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
Cha, Sang-Mok0000-0002-7511-2950
Kim, Dong-Jin0000-0002-7038-2118
Kim, Seung-Lee0000-0003-0562-5643
Lee, Yongseok0000-0001-7594-8072
Park, Byeong-Gon0000-0002-6982-7722
Pogge, Richard W.0000-0003-1435-3053
Kim, Chun-Hwey0000-0001-8591-4562
Kim, Woong-Tae0000-0003-4625-229X
Mróz, Przemek0000-0001-7016-1692
Szymański, Michał K.0000-0002-0548-8995
Skowron, Jan0000-0002-2335-1730
Poleski, Radosław0000-0002-9245-6368
Soszyński, Igor0000-0002-7777-0842
Pietrukowicz, Paweł0000-0002-2339-5899
Kozłowski, Szymon0000-0003-4084-880X
Ulaczyk, Krzysztof0000-0001-6364-408X
Rybicki, Krzysztof A.0000-0002-9326-9329
Iwanek, Patryk0000-0002-6212-7221
Wrona, Marcin0000-0002-3051-274X
Additional Information:© ESO 2021. Received 31 October 2020 / Accepted 3 February 2021. Work by C.H. was supported by the grants of National Research Foundation of Korea (2020R1A4A2002885 and 2019R1A2C2085965). Work by A.G. was supported by JPL grant 1500811. 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. The OGLE project has received funding from the National Science Centre, Poland, grant MAESTRO 2014/14/A/ST9/00121 to AU.
Funding AgencyGrant Number
National Research Foundation of Korea2020R1A4A2002885
National Research Foundation of Korea2019R1A2C2085965
National Science Centre (Poland)MAESTRO 2014/14/A/ST9/00121
Subject Keywords:gravitational lensing: micro / planets and satellites: general
Record Number:CaltechAUTHORS:20210519-141321347
Persistent URL:
Official Citation:KMT-2018-BLG-1025Lb: microlensing super-Earth planet orbiting a low-mass star Cheongho Han, Andrzej Udalski, Chung-Uk Lee, Michael D. Albrow, Sun-Ju Chung, Andrew Gould, Kyu-Ha Hwang, Youn Kil Jung, Doeon Kim, Hyoun-Woo Kim, Yoon-Hyun Ryu, In-Gu Shin, Yossi Shvartzvald, Jennifer C. Yee, Weicheng Zang, Sang-Mok Cha, Dong-Jin Kim, Seung-Lee Kim, Dong-Joo Lee, Yongseok Lee, Byeong-Gon Park, Richard W. Pogge, Chun-Hwey Kim, Woong-Tae Kim, Przemek Mróz, Michał K. Szymański, Jan Skowron, Radosław Poleski, Igor Soszyński, Paweł Pietrukowicz, Szymon Kozłowski, Krzysztof Ulaczyk, Krzysztof A. Rybicki, Patryk Iwanek and Marcin Wrona A&A, 649 (2021) A90 DOI:
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:109194
Deposited By: George Porter
Deposited On:21 May 2021 14:15
Last Modified:21 May 2021 14:15

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