OGLE-2017-BLG-0406: Spitzer Microlens Parallax Reveals Saturn-mass Planet Orbiting M-dwarf Host in the Inner Galactic Disk
Soszyński, I.; Szymański, M. K.; Pietrukowicz, P.; Skowron, J.; Mróz, P.; Poleski, R.; Kozłowski, S.; Iwanek, P.; Ulaczyk, K.; Rybicki, K.; Maoz, Dan; Lowry, S.; Tan, Thiam-Guan; 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.; Snodgrass, C.; Beichman, Charles A.; Fukui, Akihiko; KMTNet Collaboration; Gaudi, B. Scott; Southworth, J.; Kim, Hyoun-Woo; Mancini, L.; Rabus, M.; Carey, Sean; Evans, D. F.; Dominik, M.; Jørgensen, U. G.; Bozza, V.; von Essen, C.; Zhu, Wei; Sumi, Takahiro; Bond, Ian A.; Abe, Fumio; Bennett, David P.; Bhattacharya, Aparna; Donachie, Martin; Hirao, Yuki; Itow, Yoshitaka; Kondo, Iona; Koshimoto, Naoki; Li, Man Cheung Alex; Matsubara, Yutaka; Muraki, Yasushi; Miyazaki, Shota; Ranc, Clément; Rattenbury, Nicholas J.; Suzuki, Daisuke; Tristram, Paul J.; Yonehara, Atsunori; Bryden, Geoffery; Henderson, Calen B.; Spitzer Team; Peixinho, N.; Kandori, Ryo; Matsuo, Taro; Shibai, Hiroshi; Barry, Richard K.; Ciceri, S.; OGLE Collaboration; Novati, Sebastiano Calchi; Nagakane, Masayuki; Suematsu, Haruno; MOA Collaboration; Bachelet, Etienne; Burgdorf, M. J.; Skottfelt, J.; Hinse, T. C.; Rahvar, S.; McCormick, Jennie; Haikala, L.; Campbell-White, J.; Street, Rachel A.; Sajadian, S.; Fujii, Y. I.; Bolt, Greg; Hundertmark, Markus; Helling, C.; Christie, Grant; Natusch, Tim; Tsapras, Yiannis; Jaimes, R. Figuera; LCO and μFUN Follow-up Teams; MindSTEp Collaboration; IRSF Team
Japan, United States, South Korea, Poland, New Zealand, Israel, Spain, Germany, China, Canada, Australia, Denmark, United Kingdom, Italy, Sweden, Chile, Iran
Abstract
We report the discovery and analysis of the planetary microlensing event OGLE-2017-BLG-0406, which was observed both from the ground and by the Spitzer satellite in a solar orbit. At high magnification, the anomaly in the light curve was densely observed by ground-based-survey and follow-up groups, and it was found to be explained by a planetary lens with a planet/host mass ratio of $q=7.0\times {10}^{-4}$ from the light-curve modeling. The ground-only and Spitzer-"only" data each provide very strong one-dimensional (1D) constraints on the 2D microlens parallax vector ${{\boldsymbol{\pi }}}_{{\rm{E}}}$ . When combined, these yield a precise measurement of ${{\boldsymbol{\pi }}}_{{\rm{E}}}$ and of the masses of the host ${M}_{\mathrm{host}}=0.56\pm 0.07\,{M}_{\odot }$ and planet Mplanet = 0.41 ± 0.05 MJup. The system lies at a distance DL = 5.2 ± 0.5 kpc from the Sun toward the Galactic bulge, and the host is more likely to be a disk population star according to the kinematics of the lens. The projected separation of the planet from the host is ${a}_{\perp }=3.5\pm 0.3\,\mathrm{au}$ (i.e., just over twice the snow line). The Galactic-disk kinematics are established in part from a precise measurement of the source proper motion based on OGLE-IV data. By contrast, the Gaia proper-motion measurement of the source suffers from a catastrophic 10σ error.