Systematic KMTNet Planetary Anomaly Search. I. OGLE-2019-BLG-1053Lb, a Buried Terrestrial Planet
Han, Cheongho; Udalski, Andrzej; Lee, Chung-Uk; Zang, Weicheng; Albrow, Michael D.; Chung, Sun-Ju; Gould, Andrew; Hwang, Kyu-Ha; Jung, Youn Kil; Ryu, Yoon-Hyun; Shvartzvald, Yossi; Shin, In-Gu; Yee, Jennifer C.; Cha, Sang-Mok; Kim, Dong-Jin; Kim, Seung-Lee; Lee, Dong-Joo; Lee, Yongseok; Park, Byeong-Gon; Pogge, Richard W.; Mróz, Przemek; Szymański, Michał K.; Skowron, Jan; Soszyński, Igor; Pietrukowicz, Paweł; Kozłowski, Szymon; Rybicki, Krzysztof A.; Iwanek, Patryk; Ulaczyk, Krzysztof; Wrona, Marcin; Gromadzki, Mariusz; Beichman, Charles A.; Fukui, Akihiko; Gaudi, B. Scott; Kim, Hyoun-Woo; Carey, Sean; Wang, Tianshu; Zhu, Wei; Sumi, Takahiro; Mao, Shude; Zhang, Xiangyu; Poleski, Radoslaw; Bond, Ian A.; Abe, Fumio; Barry, Richard; Bennett, David P.; Bhattacharya, Aparna; Donachie, Martin; Fujii, Hirosane; 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; Bryden, Geoffery; Calchi Novati, Sebastiano; Henderson, Calen B.; Johnson, Samson; Spitzer Team
China, South Korea, Poland, United States, Japan, Germany, New Zealand, Israel, United Kingdom, Spain
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, ${M}_{\mathrm{host}}={0.61}_{-0.24}^{+0.29}\,{M}_{\odot }$ , the mass of its planet, ${M}_{\mathrm{planet}}={2.48}_{-0.98}^{+1.19}\,{M}_{\oplus }$ , the projected planet-host separation, ${a}_{\perp }={3.4}_{-0.5}^{+0.5}$ au, and the lens distance, ${D}_{{\rm{L}}}={6.8}_{-0.9}^{+0.6}$ 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.