A free-floating-planet microlensing event caused by a Saturn-mass object.
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| Title: | A free-floating-planet microlensing event caused by a Saturn-mass object. |
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| Authors: | Dong, Subo (AUTHOR), Wu, Zexuan (AUTHOR), Ryu, Yoon-Hyun (AUTHOR), Udalski, Andrzej (AUTHOR), Mróz, Przemek (AUTHOR), Rybicki, Krzysztof A. (AUTHOR), Hodgkin, Simon T. (AUTHOR), Wyrzykowski, Łukasz (AUTHOR), Eyer, Laurent (AUTHOR), Bensby, Thomas (AUTHOR), Chen, Ping (AUTHOR), Wang, Sharon X. (AUTHOR), Gould, Andrew (AUTHOR), Yang, Hongjing (AUTHOR), Albrow, Michael D. (AUTHOR), Chung, Sun-Ju (AUTHOR), Han, Cheongho (AUTHOR), Hwang, Kyu-Ha (AUTHOR), Jung, Youn Kil (AUTHOR), Shin, In-Gu (AUTHOR) |
| Source: | Science. 1/1/2026, Vol. 391 Issue 6780, p96-99. 4p. |
| Subjects: | Microlensing (Astrophysics), Gas giants, Protoplanetary disks, Gravitational lenses, Planetary systems, Gravitational interactions |
| 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 0.219 − 0.046 + 0.075 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. Editor's summary: Gravitational microlensing causes the apparent brightness of a background star to vary when a foreground object passes across our line of sight. The mass and distance of the lensing object are usually degenerate parameters. Dong et al. have identified a microlensing event caused by a planetary-mass object with no associated host star (see the Perspective by Coleman). By combining observations from Earth and a distant spacecraft, the mass-distance degeneracy can be broken, allowing for measurement of the lensing object's mass, which is similar to Saturn's. The researchers argue that this free-floating object did not form in isolation but was ejected from a host planetary system by dynamical interactions. —Keith T. Smith [ABSTRACT FROM AUTHOR] |
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| Database: | Psychology and Behavioral Sciences Collection |
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| 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 0.219 − 0.046 + 0.075 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. Editor's summary: Gravitational microlensing causes the apparent brightness of a background star to vary when a foreground object passes across our line of sight. The mass and distance of the lensing object are usually degenerate parameters. Dong et al. have identified a microlensing event caused by a planetary-mass object with no associated host star (see the Perspective by Coleman). By combining observations from Earth and a distant spacecraft, the mass-distance degeneracy can be broken, allowing for measurement of the lensing object's mass, which is similar to Saturn's. The researchers argue that this free-floating object did not form in isolation but was ejected from a host planetary system by dynamical interactions. —Keith T. Smith [ABSTRACT FROM AUTHOR] |
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| ISSN: | 00368075 |
| DOI: | 10.1126/science.adv9266 |
