{"id":25171,"date":"2024-05-20T16:00:19","date_gmt":"2024-05-20T15:00:19","guid":{"rendered":"https:\/\/ounews.co\/?p=25171"},"modified":"2024-05-20T16:00:19","modified_gmt":"2024-05-20T15:00:19","slug":"researchers-use-nasas-webb-to-cracks-case-of-inflated-exoplanet","status":"publish","type":"post","link":"https:\/\/www.open.ac.uk\/blogs\/news\/science-mct\/researchers-use-nasas-webb-to-cracks-case-of-inflated-exoplanet\/","title":{"rendered":"Researchers use NASA\u2019s JWST to crack case of inflated exoplanet"},"content":{"rendered":"

Why is the warm gas-giant exoplanet WASP-107 b so puffy? Two independent teams of researchers, including The Open University\u2019s (OU) Dr Joanna Barstow<\/a>, have an answer, published today in Nature.<\/em><\/p>\n

Data collected using NASA\u2019s James Webb Space Telescope (JWST), combined with prior observations from the Hubble Space Telescope, show surprisingly little methane (CH4<\/sub>) in the planet\u2019s atmosphere, indicating that the interior of WASP-107 b must be significantly hotter and the core much more massive than previously estimated.<\/p>\n

The unexpectedly high temperature is thought to be a result of tidal heating caused by the planet\u2019s slightly non-circular orbit, and can explain how WASP-107 b can be so inflated without resorting to extreme theories of how it formed.<\/p>\n

The results, which were made possible by Webb\u2019s extraordinary ability to analyse exoplanet atmospheres, may explain the puffiness of dozens of relatively cool, low-density exoplanets, helping solve a long-standing mystery in exoplanet science.<\/p>\n

The Problem with WASP-107 b<\/strong><\/h2>\n

At more than three-quarters the volume of Jupiter but less than one-tenth the mass, the \u201cwarm Neptune\u201d exoplanet WASP-107 b is one of the least dense planets known. While puffy planets are not uncommon, most are hotter and more massive, and therefore easier to explain.<\/p>\n

If WASP-107 b instead has a more massive core, the atmosphere should have contracted as the planet cooled over time. Without a source of heat to re-expand the gas, it should be much smaller. Although WASP-107 b has an orbital distance of just 5 million miles (one-seventh the distance between Mercury and the Sun), it doesn\u2019t receive enough energy from its star to be so inflated.<\/p>\n

A Wealth of Previously Undetectable Molecules<\/strong><\/h2>\n

WASP-107 b\u2019s giant radius, extended atmosphere, and edge-on orbit make it ideal for transmission spectroscopy, a method used to identify the various gases in an exoplanet atmosphere based on how they affect starlight.<\/p>\n

Dr Joanna Barstow, OU Research Fellow and co-author of the research, said:<\/strong><\/p>\n

\u201cWASP-107b is a great target for transit spectroscopy because it\u2019s one of the \u2018fluffiest\u2019 exoplanets we know of – its low density means the spectral features we\u2019re looking for are nice and large.\u201d<\/em><\/p><\/blockquote>\n

The remarkable precision of the data makes it possible to not just detect, but actually measure the abundances of a wealth of molecules.<\/p>\n

Roiling Gas, Hot Interior, and Massive Core<\/strong><\/h2>\n

The research showed a surprisingly lack of methane in WASP-107 b\u2019s atmosphere: one-thousandth the amount expected for a planet this cool.<\/p>\n

\u201cThis is evidence that hot gas from deep in the planet, perhaps down to the core, must be mixing vigorously with the cooler layers higher up,\u201d explained David Sing from the Johns Hopkins University (JHU). \u201cMethane is unstable at high temperature. The fact that we detected so little, even though we did detect other carbon molecules, tells us that the interior of the planet must be significantly hotter than we thought.\u201d<\/em><\/p><\/blockquote>\n

A likely source of WASP-107 b\u2019s extra internal energy is tidal heating<\/strong> caused by its slightly elliptical orbit. With the distance between the star and planet changing continuously over the 5.7-day orbit, the gravitational pull is also changing, stretching the planet and heating it up.<\/p>\n

Researchers had previously proposed that tidal heating could be the cause of WASP-107 b\u2019s puffiness, but until the Webb results were in, there was no evidence.<\/p>\n

Once they established that the planet has enough internal heat to thoroughly churn up the atmosphere, the teams realised that the spectra could also provide a new way to estimate the size of the core.<\/p>\n

It turns out that the core is more than twice as massive as originally estimated, which makes more sense in terms of how planets form.<\/p>\n

All together, it turns out that WASP-107 b is not as mysterious as it once appeared.<\/p>\n

Dr Barstow added:<\/strong><\/p>\n

“Being able to precisely measure the abundance of gases like methane provides us with really exciting insights into atmospheric dynamics on planets like WASP-107b, and JWST observations are teaching us a great deal about how planetary atmospheres work.”<\/em><\/p><\/blockquote>\n

 <\/p>\n","protected":false},"excerpt":{"rendered":"

Why is the warm gas-giant exoplanet WASP-107 b so puffy? Two independent teams of researchers, including The Open University\u2019s (OU) Dr Joanna Barstow, have an answer, published today in Nature. Data collected using NASA\u2019s James Webb Space Telescope (JWST), combined with prior observations from the Hubble Space Telescope, show surprisingly little methane (CH4) in the […]<\/p>\n","protected":false},"author":12,"featured_media":25181,"comment_status":"closed","ping_status":"closed","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[14],"tags":[861,1525,1640],"class_list":["post-25171","post","type-post","status-publish","format-standard","has-post-thumbnail","hentry","category-science-mct","tag-faculty-of-stem","tag-news-home","tag-ou-home"],"_links":{"self":[{"href":"https:\/\/www.open.ac.uk\/blogs\/news\/wp-json\/wp\/v2\/posts\/25171","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/www.open.ac.uk\/blogs\/news\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/www.open.ac.uk\/blogs\/news\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/www.open.ac.uk\/blogs\/news\/wp-json\/wp\/v2\/users\/12"}],"replies":[{"embeddable":true,"href":"https:\/\/www.open.ac.uk\/blogs\/news\/wp-json\/wp\/v2\/comments?post=25171"}],"version-history":[{"count":0,"href":"https:\/\/www.open.ac.uk\/blogs\/news\/wp-json\/wp\/v2\/posts\/25171\/revisions"}],"wp:featuredmedia":[{"embeddable":true,"href":"https:\/\/www.open.ac.uk\/blogs\/news\/wp-json\/wp\/v2\/media\/25181"}],"wp:attachment":[{"href":"https:\/\/www.open.ac.uk\/blogs\/news\/wp-json\/wp\/v2\/media?parent=25171"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/www.open.ac.uk\/blogs\/news\/wp-json\/wp\/v2\/categories?post=25171"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/www.open.ac.uk\/blogs\/news\/wp-json\/wp\/v2\/tags?post=25171"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}