MOA-2019-BLG-008Lb: A New Microlensing Detection of an Object at the Planet/Brown Dwarf Boundary
Author:
Bachelet E.ORCID, Tsapras Y.ORCID, Gould Andrew, Street R. A.ORCID, Bennett David P.ORCID, Hundertmark M. P. G., Bozza V.ORCID, Bramich D. M., Cassan A., Dominik M.ORCID, Horne K.ORCID, Mao S., Saha A.ORCID, Wambsganss J.ORCID, Zang WeichengORCID, Abe Fumio, Barry RichardORCID, Bennett David P., Bhattacharya Aparna, Bond Ian A., Fukui AkihikoORCID, Fujii Hirosane, Hirao YukiORCID, Itow YoshitakaORCID, Kirikawa Rintaro, Kondo Iona, Koshimoto NaokiORCID, Matsubara Yutaka, Matsumoto Sho, Miyazaki ShotaORCID, Muraki YasushiORCID, Olmschenk GregORCID, Ranc ClémentORCID, Okamura Arisa, Rattenbury Nicholas J.ORCID, Satoh YukiORCID, Sumi TakahiroORCID, Suzuki Daisuke, Silva Stela Ishitani, Toda Taiga, Tristram Paul . J., Vandorou AikateriniORCID, Yama Hibiki, Albrow Michael D.ORCID, Chung Sun-JuORCID, Han CheonghoORCID, Hwang Kyu-HaORCID, Jung Youn KilORCID, Ryu Yoon-HyunORCID, Shin In-GuORCID, Shvartzvald YossiORCID, Yee Jennifer C.ORCID, Cha Sang-Mok, Kim Dong-Jin, Kim Seung-LeeORCID, Lee Chung-UkORCID, Lee Dong-Joo, Lee Yongseok, Park Byeong-GonORCID, Pogge Richard W.ORCID, Udalski AndrzejORCID, Mróz PrzemekORCID, Poleski RadosławORCID, Skowron JanORCID, Szymański Michał K.ORCID, Soszyński IgorORCID, Pietrukowicz PawełORCID, Kozłowski SzymonORCID, Ulaczyk KrzysztofORCID, Rybicki Krzysztof A.ORCID, Iwanek PatrykORCID, Wrona MarcinORCID, Gromadzki MariuszORCID
Abstract
Abstract
We report on the observations, analysis and interpretation of the microlensing event MOA-2019-BLG-008. The observed anomaly in the photometric light curve is best described through a binary lens model. In this model, the source did not cross caustics and no finite-source effects were observed. Therefore, the angular Einstein ring radius θ
E cannot be measured from the light curve alone. However, the large event duration, t
E ∼ 80 days, allows a precise measurement of the microlensing parallax π
E. In addition to the constraints on the angular radius θ
* and the apparent brightness I
s
of the source, we employ the Besançon and GalMod galactic models to estimate the physical properties of the lens. We find excellent agreement between the predictions of the two galactic models: the companion is likely a resident of the brown dwarf desert with a mass M
p
∼ 30 M
Jup, and the host is a main-sequence dwarf star. The lens lies along the line of sight to the Galactic bulge, at a distance of ≤4 kpc. We estimate that in about 10 yr the lens and source will be separated by ∼55 mas, and it will be possible to confirm the exact nature of the lensing system by using high-resolution imaging from ground- or space-based observatories.
Publisher
American Astronomical Society
Subject
Space and Planetary Science,Astronomy and Astrophysics
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