A free-floating-planet microlensing event caused by a Saturn-mass object

Science 2026 Open access

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Authors: Subo Dong, Zexuan Wu, Yoon-Hyun Ryu, A. Udalski, P Mróz, Krzysztof A. Rybicki, Simon T. Hodgkin, Ł. Wyrzykowski, L. Eyer, T. Bensby, Ping Chen, Sharon X. Wang
+30 more Andrew Gould, Hongjing Yang, Michael D. Albrow, Sun-Ju Chung, Cheongho Han, Kyu-Ha Hwang, Youn Kil Jung, In-Gu Shin, Yossi Shvartzvald, Jennifer C. Yee, Weicheng Zang, Dong-Jin Kim, Chung‐Uk Lee, Byeong-Gon Park, R. Poleski, J. Skowron, M. K. Szymański, I. Soszyński, P Pietrukowicz, S Kozłowski, D. M. Skowron, K. Ulaczyk, Mariusz Gromadzki, M. Ratajczak, Patryk Iwanek, Marcin Wrona, Mateusz J. Mróz, Guy Rixon, D. L. Harrison, E. Breedt
DOI: 10.1126/science.adv9266
Cited by: 6
References: 78

Abstract

A population of free-floating planets is known from gravitational microlensing surveys. None have a directly measured mass, owing to a degeneracy with the distance, but the population statistics indicate that many are less massive than Jupiter. We report a microlensing event-KMT-2024-BLG-0792/OGLE-2024-BLG-0516, which was observed from both ground- and space-based telescopes-that breaks the mass-distance degeneracy. The event was caused by an object with [Formula: see text] Jupiter masses that is either gravitationally unbound or on a very wide orbit. Through comparison with the statistical properties of other observed microlensing events and predictions from simulations, we infer that this object likely formed in a protoplanetary disk (like a planet), not in isolation (like a brown dwarf). Dynamical processes then ejected it from its birthplace, producing a free-floating object.

Fields of Study & Subjects

Stellar planetary and galactic studies Astro and Planetary Science Astronomy and Astrophysical Research

Publication details

Journal / source
Science
Publisher
American Association for the Advancement of Science (AAAS)
Volume
391
Issue
6780
Pages
96–99
Publication date
1 January 2026
Language
EN