arXiv · 2104.02157
OGLE-2018-BLG-1185b : A Low-Mass Microlensing Planet Orbiting a Low-Mass Dwarf
Abstract
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 $\Delta f_{\rm Spz} < 4$ 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.
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Iona Kondo, Jennifer C. Yee, David P. Bennett, Takahiro Sumi, Naoki Koshimoto, Ian A. Bond, Andrew Gould, Andrzej Udalski, Yossi Shvartzvald, Youn Kil Jung, Weicheng Zang, Valerio Bozza, Etienne Bachelet, Markus P. G. Hundertmark, Nicholas J. Rattenbury, F. Abe, R. Barry, A. Bhattacharya, M. Donachie, A. Fukui, H. Fujii, Y. Hirao, S. Ishitani Silva, Y. Itow, R. Kirikawa, M. C. A. Li, Y. Matsubara, S. Miyazaki, Y. Muraki, G. Olmschenk, C. Ranc, Y. Satoh, H. Shoji, D. Suzuki, Y. Tanaka, P. J. Tristram, T. Yamawaki, A. Yonehara, P. Mróz, R. Poleski, J. Skowron, M. K. Szymański, I. Soszyński, S. Kozłowski, P. Pietrukowicz K. Ulaczyk, K. A. Rybicki, P. Iwanek, M. Wrona, M. D. Albrow, S. -J. Chung, C. Han, K. -H. Hwang, H. -W. Kim, I. -G. Shin, S. -M. Cha, D. -J. Kim, S. -L. Kim, C. -U. Lee, D. -J. Lee, Y. Lee, B. -G. Park, R. W. Pogge, Y. -H. Ryu, C. A. Beichman, G. Bryden, S. Calchi Novati, S. Carey, B. S. Gaudi, C. B. Henderson, W. Zhu, D. Maoz, M. T. Penny, M. Dominik, U. G. Jørgensen, P. Longa-Pe{\~{ n}}a, N. Peixinho, S. Sajadian, J. Skottfelt, C. Snodgrass, J. Tregloan-Reed, M. J. Burgdorf, J. Campbell-White, S. Dib, Y. I. Fujii, T. C. Hinse, E. Khalouei, S. Rahvar, M. Rabus, J. Southworth, Y. Tsapras, R. A. Street, D. M. Bramich, A. Cassan, K. Horne, J. Wambsganss, S. Mao, A. Saha. 2021-04-05. OGLE-2018-BLG-1185b : A Low-Mass Microlensing Planet Orbiting a Low-Mass Dwarf. https://doi.org/10.3847/1538-3881/ac00ba
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