OGLE-2018-BLG-1185b : A Low-Mass Microlensing Planet Orbiting a Low-Mass Dwarf
Creators: name: Kondo, Iona
name: Yee, Jennifer C.
name: Bennett, David P.
name: Sumi, Takahiro
name: Koshimoto, Naoki
name: Bond, Ian A.
name: Gould, Andrew
name: Udalski, Andrzej
name: Shvartzvald, Yossi
name: Jung, Youn Kil
name: Zang, Weicheng
name: Bozza, Valerio
name: Bachelet, Etienne
name: Hundertmark, Markus P. G.
name: Rattenbury, Nicholas J.
name: Abe, F.
name: Barry, R.
name: Bhattacharya, A.
name: Donachie, M.
name: Fukui, A.
name: Fujii, H.
name: Hirao, Y.
name: Silva, S. Ishitani
name: Itow, Y.
name: Kirikawa, R.
name: Li, M. C. A.
name: Matsubara, Y.
name: Miyazaki, S.
name: Muraki, Y.
name: Olmschenk, G.
name: Ranc, C.
name: Satoh, Y.
name: Shoji, H.
name: Suzuki, D.
name: Tanaka, Y.
name: Tristram, P. J.
name: Yamawaki, T.
name: Yonehara, A.
name: Mróz, P.
name: Poleski, R.
name: Skowron, J.
name: Szymański, M. K.
name: Soszyński, I.
name: Kozłowski, S.
name: Ulaczyk, P. Pietrukowicz K.
name: Rybicki, K. A.
name: Iwanek, P.
name: Wrona, M.
name: Albrow, M. D.
name: Chung, S. -J.
name: Han, C.
name: Hwang, K. -H.
name: Kim, H. -W.
name: Shin, I. -G.
name: Cha, S. -M.
name: Kim, D. -J.
name: Kim, S. -L.
name: Lee, C. -U.
name: Lee, D. -J.
name: Lee, Y.
name: Park, B. -G.
name: Pogge, R. W.
name: Ryu, Y. -H.
name: Beichman, C. A.
name: Bryden, G.
name: Novati, S. Calchi
name: Carey, S.
name: Gaudi, B. S.
name: Henderson, C. B.
name: Zhu, W.
name: Maoz, D.
name: Penny, M. T.
name: Dominik, M.
name: Jørgensen, U. G.
name: n}}a, P. Longa-Pe{\~{
name: Peixinho, N.
name: Sajadian, S.
name: Skottfelt, J.
name: Snodgrass, C.
name: Tregloan-Reed, J.
name: Burgdorf, M. J.
name: Campbell-White, J.
name: Dib, S.
name: Fujii, Y. I.
name: Hinse, T. C.
name: Khalouei, E.
name: Rahvar, S.
name: Rabus, M.
name: Southworth, J.
name: Tsapras, Y.
name: Street, R. A.
name: Bramich, D. M.
name: Cassan, A.
name: Horne, K.
name: Wambsganss, J.
name: Mao, S.
name: Saha, A.
Publisher: name: arXiv
Year: 2021
Subjects: subject: Earth and Planetary Astrophysics (astro-ph.EP)
subject: FOS: Physical sciences
subject: FOS: Physical sciences

description: We report the analysis of planetary microlensing event OGLE-2018-BLG-1185, which was observed by a large number of ground-based telescopes and by the $Spitzer$ Space Telescope. The ground-based light curve indicates a low planet-host star mass ratio of $q = (6.9 \pm 0.2) \times 10^{-5}$, which is near the peak of the wide-orbit exoplanet mass-ratio distribution. We estimate the host star and planet masses with a Bayesian analysis using the measured angular Einstein radius under the assumption that stars of all masses have an equal probability to host this planet. The flux variation observed by $Spitzer$ was marginal, but still places a constraint on the microlens parallax. Imposing a conservative constraint that this flux variation should be $Δf_{\rm Spz} &lt; 4$ instrumental flux units indicates a host mass of $M_{\rm host} = 0.37^{+0.35}_{-0.21}\ M_\odot$ and a planet mass of $m_{\rm p} = 8.4^{+7.9}_{-4.7}\ M_\oplus$. A Bayesian analysis including the full parallax constraint from $Spitzer$ suggests smaller host star and planet masses of $M_{\rm host} = 0.091^{+0.064}_{-0.018}\ M_\odot$ and $m_{\rm p} = 2.1^{+1.5}_{-0.4}\ M_\oplus$, respectively. Future high-resolution imaging observations with $HST$ or ELTs could distinguish between these two scenarios and help to reveal the planetary system properties in more detail.
description: 30 pages, 11 figures, 5 tables, Accepted for publication in Astronomical Journal (AJ)