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Published May 2021 | Published + Accepted Version
Journal Article Open

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

Abstract

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.

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.

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Published - aa39817-20.pdf

Accepted Version - 2102.01890.pdf

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Additional details

Created:
August 20, 2023
Modified:
October 23, 2023