KMT-2021-BLG-0912Lb: A microlensing super Earth around a K-type star

Cheongho Han, Ian A. Bond, Jennifer C. Yee, Weicheng Zang, Michael D. Albrow, Sun Ju Chung, Andrew P. Gould, Kyu Ha Hwang, Youn Kil Jung, Doeon Kim, Chung Uk Lee, Yoon Hyun Ryu, In Gu Shin, Yossi Shvartzvald, Sang Mok Cha, Dong Jin Kim, Seung Lee Kim, Dong Joo Lee, Yongseok Lee, Byeong Gon ParkRichard W. Pogge, Fumio Abe, Richard Barry, David P. Bennett, Aparna Bhattacharya, Yuki Hirao, Hirosane Fujii, Akihiko Fukui, Yoshitaka Itow, Rintaro Kirikawa, Iona Kondo, Naoki Koshimoto, Yutaka Matsubara, Sho Matsumoto, Yasushi Muraki, Shota Miyazaki, Clément Ranc, Arisa Okamura, Nicholas J. Rattenbury, Yuki Satoh, Takahiro Sumi, Daisuke Suzuki, Stela Ishitani Silva, Taiga Toda, Paul J. Tristram, Hibiki Yama, Atsunori Yonehara, Tony Cooper, Plamen Dimitrov, Subo Dong, John Drummond, Jonathan Green, Steve Hennerley, Zhuokai Liu, Shude Mao, Dan Maoz, Matthew Penny, Hongjing Yang

Research output: Contribution to journalArticlepeer-review


Aims. The light curve of the microlensing event KMT-2021-BLG-0912 exhibits a very short anomaly relative to a single-lens single-source form. We investigate the light curve for the purpose of identifying the origin of the anomaly. Methods. We model the light curve under various interpretations. From this, we find four solutions, in which three solutions are found underthe assumption that the lens is composed of two masses (2L1S models), and the other solution is found under the assumption that the source is comprised of binary stars (1L2S model). The 1L2S model is ruled out based on the contradiction that the faint source companion is bigger than its primary, and one of the 2L1S solutions is excluded from the combination of the poorer fit, blending constraint, and lower overall probability, leaving two surviving solutions with the planet/host mass ratios of q 2.8 × 10-5 and 1.1 × 10-5. A subtle central deviation supports the possibility of a tertiary lens component, either a binary companion to the host with a very large or small separation, or a second planet lying near the Einstein ring, but it is difficult to claim a secure detection due to the marginal improvement of the fit, lack of consistency among different data sets, and difficulty in uniquely specifying the nature of the tertiary component. Results. With the observables of the event, it is estimated that the masses of the planet and host are (6.9 M, 0.75 M) according to one solution and~(2.8 M, 0.80 M) according to the other, indicating that the planet is a super Earth around a K-type star, regardless of the solution. The fact that 16 (including the one reported in this work) out of 19 microlensing planets with M10 M were detected during the last 6 yr nicely demonstrates the importance of high-cadence global surveys in detecting very low-mass planets.

Original languageEnglish
Article numberA94
JournalAstronomy and Astrophysics
StatePublished - 1 Feb 2022


  • Gravitational lensing
  • Planets and satellites
  • detection
  • micro

All Science Journal Classification (ASJC) codes

  • Astronomy and Astrophysics
  • Space and Planetary Science


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