KMT-2021-BLG-0912Lb: A microlensing super Earth around a K-type star
Creators: name: Han, Cheongho
name: Bond, Ian A.
name: Yee, Jennifer C.
name: Zang, Weicheng
name: Albrow, Michael D.
name: Chung, Sun-Ju
name: Gould, Andrew P.
name: Hwang, Kyu-Ha
name: Jung, Youn Kil
name: Kim, Doeon
name: Lee, Chung-Uk
name: Ryu, Yoon-Hyun
name: Shin, In-Gu
name: Shvartzvald, Yossi
name: Cha, Sang-Mok
name: Kim, Dong-Jin
name: Kim, Seung-Lee
name: Lee, Dong-Joo
name: Lee, Yongseok
name: Park, Byeong-Gon
name: Pogge, Richard W.
name: Abe, Fumio
name: Barry, Richard
name: Bennett, David P.
name: Bhattacharya, Aparna
name: Hirao, Yuki
name: Fujii, Hirosane
name: Fukui, Akihiko
name: Itow, Yoshitaka
name: Kirikawa, Rintaro
name: Kondo, Iona
name: Koshimoto, Naoki
name: Matsubara, Yutaka
name: Matsumoto, Sho
name: Muraki, Yasushi
name: Miyazaki, Shota
name: Ranc, Clément
name: Okamura, Arisa
name: Rattenbury, Nicholas J.
name: Satoh, Yuki
name: Sumi, Takahiro
name: Suzuki, Daisuke
name: Silva, Stela Ishitani
name: Toda, Taiga
name: Tristram, Paul J.
name: Yama, Hibiki
name: Yonehara, Atsunori
name: Cooper, Tony
name: Dimitrov, Plamen
name: Dong, Subo
name: Drummond, John
name: Green, Jonathan
name: Hennerley, Steve
name: Liu, Zhuokai
name: Mao, Shude
name: Maoz, Dan
name: Penny, Matthew
name: Yang, Hongjing
Publisher: name: arXiv
Year: 2021
Subjects: subject: Earth and Planetary Astrophysics (astro-ph.EP)
subject: Astrophysics of Galaxies (astro-ph.GA)
subject: FOS: Physical sciences
subject: FOS: Physical sciences

description: 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. We model the light curve under various interpretations. From this, we find four solutions, in which three solutions are found under the 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 a binary-star system (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 relatively worse fit, blending constraint, and lower overall probability, leaving two surviving solutions with the planet/host mass ratios of $q\sim 2.8\times 10^{-5}$ and $\sim 1.1\times 10^{-5}$. 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 fit improvement, lack of consistency among different data sets, and difficulty in uniquely specifying the nature of the tertiary component. With the observables of the event, it is estimated that the masses of the planet and host are $\sim (6.9~M_\oplus, 0.75~M_\odot)$ according to one solution and $\sim (2.8~M_\oplus, 0.80~M_\odot)$ according to the other solution, indicating that the planet is a super Earth around a K-type star, regardless of the solution.
description: 11 pages, 10 figures, 7 tables