{"id":271545,"date":"2026-01-07T04:25:17","date_gmt":"2026-01-07T04:25:17","guid":{"rendered":"https:\/\/www.europesays.com\/ie\/271545\/"},"modified":"2026-01-07T04:25:17","modified_gmt":"2026-01-07T04:25:17","slug":"astronomers-measure-mass-of-free-floating-exoplanet-for-first-time","status":"publish","type":"post","link":"https:\/\/www.europesays.com\/ie\/271545\/","title":{"rendered":"Astronomers Measure Mass of Free-Floating Exoplanet for First Time"},"content":{"rendered":"

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. Now, astronomers have discovered a microlensing event that breaks the mass-distance degeneracy. Designated KMT-2024-BLG-0792\/OGLE-2024-BLG-0516, the event was caused by an exoplanet about 21.9% the mass of Jupiter at a distance of 9,785 light-years (3,000 parsecs) from the center of our Milky Way Galaxy.<\/strong><\/p>\n

\"An<\/p>\n

An artist\u2019s impression of a free-floating exoplanet. Image credit: Sci.News.<\/p>\n

Planets are most often found bound to one or more stars, yet a growing body of evidence shows that some wander the galaxy alone.<\/p>\n

These objects, called free-floating or rogue planets, lack any known stellar companion.<\/p>\n

And, since they don\u2019t emit very much light, they reveal themselves only through their subtle gravitational effects \u2014 a phenomenon called microlensing.<\/p>\n

One of the main limitations of this discovery method is that it cannot determine the distance to these planets, making independent measurement of their mass difficult.<\/p>\n

As a result, much about this elusive population of solitary worlds remains speculative.<\/p>\n

In new research, Dr. Subo Dong, an astronomer at Peking University and the National Astronomical Observatories, and colleagues detected a new free-floating planet via a fleeting microlensing event: KMT-2024-BLG-0792\/OGLE-2024-BLG-0516.<\/p>\n

However, unlike previous detections, they uniquely observed this microlensing event simultaneously from both Earth and space, using several ground-based surveys alongside ESA\u2019s Gaia space telescope.<\/p>\n

Tiny differences in the timing of the light reaching these distantly separated vantage points enabled measurement of the microlensing parallax, which, when combined with finite-source point-lens modeling, allowed the authors to determine the planet\u2019s mass and location.<\/p>\n

\u201cThrough 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),\u201d the astronomers said.<\/p>\n

\u201cDynamical processes then ejected it from its birthplace, producing a free-floating object.\u201d<\/p>\n

The results are described in a paper<\/a> published this month in the journal Science.<\/p>\n

_____<\/p>\n

Subo Dong et al. 2026. A free-floating-planet microlensing event caused by a Saturn-mass object. Science 391 (6780): 96-99; doi: 10.1126\/science.adv9266<\/p>\n","protected":false},"excerpt":{"rendered":"A population of free-floating planets is known from gravitational microlensing surveys. None have a directly measured mass, owing…\n","protected":false},"author":2,"featured_media":271546,"comment_status":"","ping_status":"","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[270],"tags":[18,6145,18060,138274,134465,138275,19,17,45128,138276,133,451],"class_list":{"0":"post-271545","1":"post","2":"type-post","3":"status-publish","4":"format-standard","5":"has-post-thumbnail","7":"category-space","8":"tag-eire","9":"tag-esa","10":"tag-exoplanet","11":"tag-free-floating-planet","12":"tag-gaia-satellite","13":"tag-gravitational-lens","14":"tag-ie","15":"tag-ireland","16":"tag-mass","17":"tag-microlensing","18":"tag-science","19":"tag-space"},"share_on_mastodon":{"url":"https:\/\/pubeurope.com\/@ie\/115851920906676413","error":""},"_links":{"self":[{"href":"https:\/\/www.europesays.com\/ie\/wp-json\/wp\/v2\/posts\/271545","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/www.europesays.com\/ie\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/www.europesays.com\/ie\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/www.europesays.com\/ie\/wp-json\/wp\/v2\/users\/2"}],"replies":[{"embeddable":true,"href":"https:\/\/www.europesays.com\/ie\/wp-json\/wp\/v2\/comments?post=271545"}],"version-history":[{"count":0,"href":"https:\/\/www.europesays.com\/ie\/wp-json\/wp\/v2\/posts\/271545\/revisions"}],"wp:featuredmedia":[{"embeddable":true,"href":"https:\/\/www.europesays.com\/ie\/wp-json\/wp\/v2\/media\/271546"}],"wp:attachment":[{"href":"https:\/\/www.europesays.com\/ie\/wp-json\/wp\/v2\/media?parent=271545"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/www.europesays.com\/ie\/wp-json\/wp\/v2\/categories?post=271545"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/www.europesays.com\/ie\/wp-json\/wp\/v2\/tags?post=271545"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}