{"id":9624,"date":"2025-06-04T10:03:16","date_gmt":"2025-06-04T14:03:16","guid":{"rendered":"https:\/\/spaceandplanetarynewswire.com\/?p=9624"},"modified":"2025-06-04T10:03:16","modified_gmt":"2025-06-04T14:03:16","slug":"a-giant-planet-around-a-tiny-star-a-discovery-that-challenges-planet-formation-theories","status":"publish","type":"post","link":"https:\/\/spaceandplanetarynewswire.com\/?p=9624","title":{"rendered":"A Giant Planet Around a Tiny Star: A Discovery That Challenges Planet Formation Theories"},"content":{"rendered":"

An international team of astronomers, including researchers from the University of Li\u00e8ge and collaborators in UK, Chile, the USA, and Europe, has discovered a giant planet orbiting the smallest known star to host such a companion<\/strong><\/em><\/p>\n

TOI-6894b Exoplanet – artist’s impression<\/figcaption><\/figure>\n

The host star, TOI-6894, is a red dwarf with only 20% the mass of the Sun, typical of the most common stars in our galaxy. Until now, such low-mass stars were not thought capable of forming or retaining giant planets. But as published<\/a> today in Nature Astronomy<\/em>, the unmistakable signature of a giant planet \u2014 TOI-6894b \u2014 has been detected in orbit around this tiny star.<\/p>\n

This exceptional system was first identified in data from NASA\u2019s Transiting Exoplanet Survey Satellite (TESS), as part of a large search for giant planets around small stars, led by Dr. Edward Bryant from UCL\u2019s Mullard Space Science Laboratory.<\/p>\n

The planetary nature of the signal was then confirmed by an extensive ground-based observation campaign, involving several telescopes \u2014 including those of the SPECULOOS and TRAPPIST projects, both led by the University of Li\u00e8ge.<\/p>\n

Dr. Khalid Barkaoui, researcher on the SPECULOOS and TRAPPIST teams, oversaw these crucial follow-up observations. He explained: \u201cThe transit signal was unambiguous in our data. Our analysis ruled out all alternative explanations \u2014 the only viable scenario was that this tiny star hosts a Saturn-sized planet with an orbital period of just over three days. Additional observations confirmed that its mass is about half that of Saturn. This is clearly a giant planet.\u201d<\/p>\n

TOI-6894 is now the smallest star known to host a transiting giant planet, with a radius 40% smaller than that of any previous such host.<\/p>\n

Prof. Jamila Chouquar, who was an astronomer at ULiege at the time of the discovery, added: \u201cWe previously believed that stars this small couldn\u2019t form or hold on to giant planets. But stars like TOI-6894 are the most common type in the Milky Way \u2014 so our discovery suggests there may be far more giant planets out there than we thought.\u201d<\/p>\n

A Challenge to Planet Formation Models<\/strong><\/p>\n

According to current planet formation models, giant planets are rare around small stars. This is because their protoplanetary disks \u2014 the gas and dust reservoirs from which planets form \u2014 are thought to lack the material needed to build massive cores and accrete thick gas envelopes.<\/p>\n

Dr. Mathilde Timmermans, member of the SPECULOOS team and ULiege astronomer at the time of the discovery, noted: \u201cThe existence of TOI-6894b is hard to reconcile with existing models. None can fully explain how it formed. This shows that our understanding is incomplete, and underscores the need to find more such planets. That\u2019s exactly the goal of MANGO, a SPECULOOS sub-program led by myself and Dr. Georgina Dransfield at the University of Birmingham.\u201d<\/p>\n

Prof. Micha\u00ebl Gillon,Fund for Scientific Research – FNRS Research Director at ULiege and head of the SPECULOOS and TRAPPIST programs, concluded: \u201cThis giant planet orbiting a tiny star reveals that planetary diversity in the galaxy is even greater than we imagined. Most of the targets observed by SPECULOOS and TRAPPIST are similar stars, or even smaller \u2014 so we\u2019re well positioned to uncover more cosmic outliers in the years ahead.\u201d<\/p>\n","protected":false},"excerpt":{"rendered":"

An international team of astronomers, including researchers from the University of Li\u00e8ge and collaborators in UK, Chile, the USA, and Europe, has discovered a giant planet orbiting the smallest known star to host such a companion The host star, TOI-6894, is a red dwarf with only 20% the mass of the Sun, typical of the…<\/p>\n","protected":false},"author":71,"featured_media":9625,"comment_status":"open","ping_status":"closed","sticky":false,"template":"","format":"standard","meta":{"ngg_post_thumbnail":0,"fifu_image_url":"https:\/\/mediasvc.eurekalert.org\/Api\/v1\/Multimedia\/0ff7fb03-8d41-4faf-8fc8-204f01a5f5d2\/Rendition\/low-res\/Content\/Public","fifu_image_alt":"","footnotes":""},"categories":[216],"tags":[],"class_list":["post-9624","post","type-post","status-publish","format-standard","has-post-thumbnail","hentry","category-discovery"],"_links":{"self":[{"href":"https:\/\/spaceandplanetarynewswire.com\/index.php?rest_route=\/wp\/v2\/posts\/9624","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/spaceandplanetarynewswire.com\/index.php?rest_route=\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/spaceandplanetarynewswire.com\/index.php?rest_route=\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/spaceandplanetarynewswire.com\/index.php?rest_route=\/wp\/v2\/users\/71"}],"replies":[{"embeddable":true,"href":"https:\/\/spaceandplanetarynewswire.com\/index.php?rest_route=%2Fwp%2Fv2%2Fcomments&post=9624"}],"version-history":[{"count":1,"href":"https:\/\/spaceandplanetarynewswire.com\/index.php?rest_route=\/wp\/v2\/posts\/9624\/revisions"}],"predecessor-version":[{"id":9626,"href":"https:\/\/spaceandplanetarynewswire.com\/index.php?rest_route=\/wp\/v2\/posts\/9624\/revisions\/9626"}],"wp:featuredmedia":[{"embeddable":true,"href":"https:\/\/spaceandplanetarynewswire.com\/index.php?rest_route=\/wp\/v2\/media\/9625"}],"wp:attachment":[{"href":"https:\/\/spaceandplanetarynewswire.com\/index.php?rest_route=%2Fwp%2Fv2%2Fmedia&parent=9624"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/spaceandplanetarynewswire.com\/index.php?rest_route=%2Fwp%2Fv2%2Fcategories&post=9624"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/spaceandplanetarynewswire.com\/index.php?rest_route=%2Fwp%2Fv2%2Ftags&post=9624"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}