OGLE-2016-BLG-0523: A Low-mass Brown Dwarf or Super-Jupiter in a >100 au Orbit

Abstract To search for very wide-orbit binary-lens events, we crossmatch microlensing events detected by the Optical Gravitational Lensing Experiment (OGLE)-IV and KMTNet between 2011 and 2024. After removing contaminants from variable stars, we identify OGLE-2016-BLG-0523 as a microlensing event showing two short-lived bumps in its light curve, with the two separated by 8.36 yr. We investigate three scenarios to explain the two bumps, including a binary-lens single-source (2L1S), a single-lens binary-source (1L2S), and two unrelated single-lens single-source events (2×1L1S). The 1L2S interpretation is excluded due to its poorer fit to the data, while the 2×1L1S scenario is disfavored by the low event rate, unphysical total source flux, and unphysical color for one of the two putative sources. For the surviving 2L1S interpretation, the Einstein timescales of the two bumps are 8.343 ± 0.076 days and 3.231 ± 0.047 days, respectively, implying a binary mass ratio of q = 0.15. A Bayesian analysis indicates that the primary lens is most likely a low-mass M dwarf, while the companion is probably a low-mass brown dwarf or super-Jupiter. The inferred projected separation is about 450 au, making the companion the widest low-mass object discovered via microlensing to date. Our discovery highlights both the promise and challenges of identifying very wide, low-mass companions through microlensing. Although upcoming facilities such as Roman and Earth 2.0 space telescopes will improve sensitivity to such events, overcoming degeneracies and distinguishing them from variable phenomena will remain essential for building a robust statistical sample.

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Journal
The Astrophysical Journal Letters
Published
2026-10-27
DOI
https://doi.org/10.3847/2041-8213/aeb37b
Primary Topic
Stellar, planetary, and galactic studies
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article
Field-Weighted Citation Impact
0.00

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article

OGLE-2016-BLG-0523: A Low-mass Brown Dwarf or Super-Jupiter in a >100 au Orbit

Sang-Mok Cha, Yongseok Lee, I. Soszyński, Michael D. Albrow et al.
1 links
The Astrophysical Journal Letters
Stellar, planetary, and galactic studies
article

OGLE-2016-BLG-0523: A Low-mass Brown Dwarf or Super-Jupiter in a >100 au Orbit

Sang-Mok Cha, Yongseok Lee, I. Soszyński, Michael D. Albrow, Weicheng Zang, Hongjing Yang, Mariusz Gromadzki, Kyu‐Ha Hwang, Shude Mao, Krzysztof A. Rybicki, Michał K. Szymański, J. Skowron, Byeong-Gon Park, R. Poleski, Yoon-Hyun Ryu, Yossi Shvartzvald, Seung‐Lee Kim, Chung‐Uk Lee, Dong-Joo Lee, Sun‐Ju Chung, Cheongho Han, Andrzej Udalski, Youn Kil Jung, Qiyue Qian, Patryk Iwanek, Paweł Pietrukowicz, Przemek Mróz, Krzysztof Ulaczyk, Hyoun-Woo Kim, In-Gu Shin, Jennifer C. Yee, Szymon Kozłowski, Richard W. Pogge, Marcin Wrona, Mateusz J. Mróz, Jiyuan Zhang, Hongyu Li, Andrew P. Gould, Doeon Kim, Yuchen Tang
article en

Abstract

Abstract To search for very wide-orbit binary-lens events, we crossmatch microlensing events detected by the Optical Gravitational Lensing Experiment (OGLE)-IV and KMTNet between 2011 and 2024. After removing contaminants from variable stars, we identify OGLE-2016-BLG-0523 as a microlensing event showing two short-lived bumps in its light curve, with the two separated by 8.36 yr. We investigate three scenarios to explain the two bumps, including a binary-lens single-source (2L1S), a single-lens binary-source (1L2S), and two unrelated single-lens single-source events (2×1L1S). The 1L2S interpretation is excluded due to its poorer fit to the data, while the 2×1L1S scenario is disfavored by the low event rate, unphysical total source flux, and unphysical color for one of the two putative sources. For the surviving 2L1S interpretation, the Einstein timescales of the two bumps are 8.343 ± 0.076 days and 3.231 ± 0.047 days, respectively, implying a binary mass ratio of q = 0.15. A Bayesian analysis indicates that the primary lens is most likely a low-mass M dwarf, while the companion is probably a low-mass brown dwarf or super-Jupiter. The inferred projected separation is about 450 au, making the companion the widest low-mass object discovered via microlensing to date. Our discovery highlights both the promise and challenges of identifying very wide, low-mass companions through microlensing. Although upcoming facilities such as Roman and Earth 2.0 space telescopes will improve sensitivity to such events, overcoming degeneracies and distinguishing them from variable phenomena will remain essential for building a robust statistical sample.

The Astrophysical Journal LettersVol. 1011(1)
Chungbuk National University (KR), University of Canterbury (NZ), Korea Astronomy and Space Science Institute (KR), Westlake University (CN), Kyung Hee University (KR), University of Warwick (GB), Max Planck Institute for Astronomy (DE), Center for Astrophysics Harvard & Smithsonian (US), University of Warsaw (PL), The Ohio State University (US), Weizmann Institute of Science (IL), Villanova University (US), Tsinghua University (CN)
National Natural Science Foundation of China, China Postdoctoral Science Foundation, Korea Astronomy and Space Science Institute, National Research Foundation of Korea, Ministry of Science and ICT, South Korea, Korea Research Environment Open Network
Openalex Percentile: Top 14%
Stellar, planetary, and galactic studies
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