Systematic KMTNet Planetary Anomaly Search. I. OGLE-2019-BLG-1053Lb, a Buried Terrestrial Planet

Creators: Zang, Weicheng; Hwang, Kyu-Ha; Udalski, Andrzej; Wang, Tianshu; Zhu, Wei; Sumi, Takahiro; Yee, Jennifer C.; Gould, Andrew; Mao, Shude; Zhang, Xiangyu; Albrow, Michael D.; Chung, Sun-Ju; Han, Cheongho; Jung, Youn Kil; Ryu, Yoon-Hyun; Shin, In-Gu; Shvartzvald, Yossi; 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.; Mróz, Przemek; Skowron, Jan; Poleski, Radoslaw; Szymański, Michał-K.; Soszyński, Igor; Pietrukowicz, Paweł; Kozłowski, Szymon; Ulaczyk, Krzysztof; Rybicki, Krzysztof A.; Iwanek, Patryk; Wrona, Marcin; Gromadzki, Mariusz; Bond, Ian A.; Abe, Fumio; Barry, Richard; Bennett, David P.; Bhattacharya, Aparna; Donachie, Martin; Fujii, Hirosane; Fukui, Akihiko; Hirao, Yuki; Itow, Yoshitaka; Kirikawa, Rintaro; Kondo, Iona; Koshimoto, Naoki; Li, Man Cheung Alex; Matsubara, Yutaka; Muraki, Yasushi; Miyazaki, Shota; Olmschenk, Greg; Ranc, Clément; Rattenbury, Nicholas J.; Satoh, Yuki; Shoji, Hikaru; Ishitani Silva, Stela; Suzuki, Daisuke; Tanaka, Yuzuru; Tristram, Paul J.; Yamawaki, Tsubasa; Yonehara, Atsunori; Beichman, Charles A.; Bryden, Geoffery; Calchi Novati, Sebastiano; Carey, Sean; Gaudi, B. Scott; Henderson, Calen B.; Johnson, Samson A.; KMTNet Collaboration; OGLE Collaboration; MOA Collaboration; Spitzer Team

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Abstract

In order to exhume the buried signatures of "missing planetary caustics" in Korea Microlensing Telescope Network (KMTNet) data, we conducted a systematic anomaly search of the residuals from point-source point-lens fits, based on a modified version of the KMTNet EventFinder algorithm. This search revealed the lowest-mass-ratio planetary caustic to date in the microlensing event OGLE-2019-BLG-1053, for which the planetary signal had not been noticed before. The planetary system has a planet–host mass ratio of q = (1.25 ± 0.13) × 10⁻⁵. A Bayesian analysis yielded estimates of the mass of the host star, M_(host) = 0.61^(+0.29)_(−0.24) M_⊙, the mass of its planet, M_(planet) = 2.48^(+1.19)_(−0.98) M_⊕, the projected planet–host separation, a_⊥=3.4^(+0.5)_(−0.5) au, and the lens distance, D_L = 6.8^(+0.6)_(−0.9) kpc. The discovery of this very-low-mass-ratio planet illustrates the utility of our method and opens a new window for a large and homogeneous sample to study the microlensing planet–host mass ratio function down to q ∼ 10⁻⁵.

Additional Information

© 2021. The American Astronomical Society. Received 2021 May 28; revised 2021 June 24; accepted 2021 July 7; published 2021 September 24. W.Z., S.M., and X.Z. acknowledge support from the National Science Foundation of China (grant Nos. 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 the three host sites of CTIO in Chile, SAAO in South Africa, and SSO in Australia. OGLE has received funding from the National Science Centre, Poland, grant MAESTRO 2014/14/A/ST9/00121 to A.U. The MOA project is supported by JSPS KAKENHI grant Nos. JSPS24253004, JSPS26247023, JSPS23340064, JSPS15H00781, JP16H06287, JP17H02871, and JP19KK0082. Work by J.C.Y. was supported by Jet Propulsion Laboratory grant 1571564. Work by C.H. was supported by grants of the National Research Foundation of Korea (2019R1A2C2085965 and 2020R1A4A2002885). This research has made use of the NASA Exoplanet Archive, which is operated by the California Institute of Technology, under a contract with the National Aeronautics and Space Administration under the Exoplanet Exploration Program. Software: pySIS (Albrow et al. 2009), pyDIA (Zenodo, doi:10.5281/zenodo.268049, as developed on GitHub), OGLE DIA pipeline (Wozniak 2000), Spitzer photometry software (Calchi Novati et al. 2015b).

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