Tiny star hosts a giant TOI-6894b TOI-6894 is a cool red dwarf<\/a> that shines with far less light than the Sun. Yet its companion, TOI-6894b, is a puffed-up gas world whose radius exceeds Saturn\u2019s while its mass is only half as large.<\/p>\n \u201cI was very excited by this discovery. I originally searched through TESS observations of more than 91,000 low-mass red dwarf stars looking for giant planets,\u201d said lead author Edward Bryant, an astronomer at University College London (UCL<\/a>).<\/p>\n \u201cThen, using observations taken with one of the world\u2019s largest telescopes, ESO\u2019s VLT<\/a>, I discovered TOI-6894b, a giant planet transiting the lowest-mass star known to date to host such a planet.<\/p>\n \u201cWe did not expect planets like TOI-6894b to be able to form around stars this low-mass. This discovery will be a cornerstone for understanding the extremes of giant planet formation.\u201d<\/p>\n Star and planet mismatch<\/p>\n The host star is 60 percent smaller than the next-tiniest star known to harbor a transiting gas giant. That fact alone forces astronomers to rethink estimates of planetary populations.<\/p>\n \u201cMost stars in our galaxy are actually small stars exactly like this, with low masses and previously thought to not be able to host gas giant planets,\u201d said co-author Daniel Bayliss, an astrophysicist at the University of Warwick<\/a>.<\/p>\n \u201cSo, the fact that this star hosts a giant planet has big implications for the total number of giant planets in our Galaxy.\u201d <\/p>\n TOI-6894b is a mystery<\/p>\n Standard core-accretion theory struggles to explain the new object. Low-mass stars should possess thin disks that cannot build hefty planetary cores before the gas disperses.<\/p>\n \u201cIt\u2019s an intriguing discovery. We don\u2019t really understand how a star with so little mass can form such a massive planet!\u201d said co-author Vincent Van Eylen, an expert in exoplanets at UCL.<\/p>\n \u201cThis is one of the goals of the search for more exoplanets. By finding planetary systems different from our solar <\/a>s<\/a>ystem<\/a>, we can test our models and better understand how our own solar system formed.\u201d<\/p>\n The team explored two alternate routes. \u201cGiven the mass of the planet TOI-6894b could have formed through an intermediate core-accretion process,\u201d Bryant said.<\/p>\n Alternatively, the planet could have formed when a gravitationally unstable disc fragmented under its own gravity, leading gas and dust to collapse into a planet. However, neither scenario fits the present data perfectly, keeping the planet\u2019s origin open.<\/p>\n Gas giant details emerge<\/p>\n TOI-6894b orbits at a distance that leaves its atmosphere chilly by exoplanet standards. The estimated equilibrium temperature is only 420 Kelvin.<\/p>\n \u201cBased on the stellar irradiation of TOI-6894b, we expect the atmosphere is dominated by methane chemistry, which is exceedingly rare to identify,\u201d said co-author Amaury Triaud, an astrophysicist at the University of Birmingham<\/a>.<\/p>\n Temperatures could allow ammonia<\/a> to be detected in an exoplanet atmosphere for the first time.<\/p>\n \u201cTOI-6894b likely presents a benchmark exoplanet for the study of methane-dominated atmospheres and the best \u2018laboratory\u2019 to study a planetary atmosphere containing carbon, nitrogen, and oxygen outside the Solar System,\u201d he said. <\/p>\n Such promise has already earned the planet a place in the James Webb Space Telescope (JWST<\/a>) observing queue. Spectra next year may reveal the gas balance and cloud depth, shedding light on the planet\u2019s formation.<\/p>\n TOI-6894b opens new star search lanes<\/p>\n \u201cThis system provides a new challenge for models of planet formation<\/a>,\u201d said co-author Andr\u00e9s Jord\u00e1n, an astrophysicist at the University Adolfo Ib\u00e1\u00f1ez<\/a>. \u201cIt offers a very interesting target for follow-up observations to characterize its atmosphere.\u201d<\/p>\n \u201cOur efforts have allowed us to contribute significantly to a better understanding of how often small stars can form giant planets, and we are providing prime targets for follow-up with space-based platforms.\u201d<\/p>\n Every sentence of data from TOI-6894b will sharpen those statistics. If many dim red dwarfs host similar planets, the Milky Way could have more gas giants than expected.<\/p>\n For now, the new world stands as a reminder that planet formation remains flexible \u2013 and sometimes spectacularly bold \u2013 no matter how modest the parent star.<\/p>\n \u2014\u2013<\/p>\n This research was led by researchers at the University of Warwick<\/a>, University College London\u2019s (UCL) Mullard Space Science Laboratory<\/a>, the University of Birmingham<\/a>, and other partners.<\/p>\n The study is published in the journal Nature Astronomy<\/a>.<\/p>\n Image credit: University of Warwick\/Mark Garlick<\/p>\n \u2014\u2013<\/p>\n Like what you read? Subscribe to our newsletter<\/a> for engaging articles, exclusive content, and the latest updates.<\/p>\n Check us out on EarthSnap<\/a>, a free app brought to you by Eric Ralls<\/a> and Earth.com.<\/p>\n \u2014\u2013<\/p>\n","protected":false},"excerpt":{"rendered":"Astronomers have spotted a giant exoplanet, named TOI-6894b, that\u2019s bigger than Saturn and circling a red dwarf star…\n","protected":false},"author":2,"featured_media":305731,"comment_status":"","ping_status":"","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[23],"tags":[85,46,141,145],"class_list":["post-305730","post","type-post","status-publish","format-standard","has-post-thumbnail","category-space","tag-il","tag-israel","tag-science","tag-space"],"_links":{"self":[{"href":"https:\/\/www.newsbeep.com\/il\/wp-json\/wp\/v2\/posts\/305730","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/www.newsbeep.com\/il\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/www.newsbeep.com\/il\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/www.newsbeep.com\/il\/wp-json\/wp\/v2\/users\/2"}],"replies":[{"embeddable":true,"href":"https:\/\/www.newsbeep.com\/il\/wp-json\/wp\/v2\/comments?post=305730"}],"version-history":[{"count":0,"href":"https:\/\/www.newsbeep.com\/il\/wp-json\/wp\/v2\/posts\/305730\/revisions"}],"wp:featuredmedia":[{"embeddable":true,"href":"https:\/\/www.newsbeep.com\/il\/wp-json\/wp\/v2\/media\/305731"}],"wp:attachment":[{"href":"https:\/\/www.newsbeep.com\/il\/wp-json\/wp\/v2\/media?parent=305730"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/www.newsbeep.com\/il\/wp-json\/wp\/v2\/categories?post=305730"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/www.newsbeep.com\/il\/wp-json\/wp\/v2\/tags?post=305730"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}
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