MOA-2019-BLG-008Lb: A New Microlensing Detection of an Object at the Planet/Brown Dwarf Boundary

September 2022 • 2022AJ....164...75B

Authors • Bachelet, E. • Tsapras, Y. • Gould, Andrew • Street, R. A. • Bennett, David P. • Hundertmark, M. P. G. • Bozza, V. • Bramich, D. M. • Cassan, A. • Dominik, M. • Horne, K. • Mao, S. • Saha, A. • Wambsganss, J. • Zang, Weicheng • ROME/REA Collaboration • Abe, Fumio • Barry, Richard • Bennett, David P. • Bhattacharya, Aparna • Bond, Ian A. • Fukui, Akihiko • Fujii, Hirosane • Hirao, Yuki • Itow, Yoshitaka • Kirikawa, Rintaro • Kondo, Iona • Koshimoto, Naoki • Matsubara, Yutaka • Matsumoto, Sho • Miyazaki, Shota • Muraki, Yasushi • Olmschenk, Greg • Ranc, Clément • Okamura, Arisa • Rattenbury, Nicholas J. • Satoh, Yuki • Sumi, Takahiro • Suzuki, Daisuke • Silva, Stela Ishitani • Toda, Taiga • Tristram, Paul. J. • Vandorou, Aikaterini • Yama, Hibiki • MOA Collaboration • Albrow, Michael D. • Chung, Sun-Ju • Han, Cheongho • Hwang, Kyu-Ha • Jung, Youn Kil • Ryu, Yoon-Hyun • Shin, In-Gu • Shvartzvald, Yossi • Yee, Jennifer C. • Cha, Sang-Mok • Kim, Dong-Jin • Kim, Seung-Lee • Lee, Chung-Uk • Lee, Dong-Joo • Lee, Yongseok • Park, Byeong-Gon • Pogge, Richard W. • KMTNet Collaboration • Udalski, Andrzej • Mróz, Przemek • Poleski, Radosław • Skowron, Jan • Szymański, Michał K. • Soszyński, Igor • Pietrukowicz, Paweł • Kozłowski, Szymon • Ulaczyk, Krzysztof • Rybicki, Krzysztof A. • Iwanek, Patryk • Wrona, Marcin • Gromadzki, Mariusz • OGLE Collaboration

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.

Links

• SIMBAD http://simbad.u-strasbg.fr/simbo.pl?bibcode=2022AJ....164...75B
• DATA http://cdsarc.cds.unistra.fr/viz-bin/cat/J/AJ/164/75
• PREPRINT http://arxiv.org/abs/2205.07522
• ELECTR https://doi.org/10.3847%2F1538-3881%2Fac78ed