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dc.contributor.authorNixon, MC
dc.contributor.authorNikku, Madhusudhan
dc.date.accessioned2022-01-11T00:32:20Z
dc.date.available2022-01-11T00:32:20Z
dc.date.issued2021-08
dc.identifier.issn0035-8711
dc.identifier.urihttps://www.repository.cam.ac.uk/handle/1810/332606
dc.description.abstractUnderstanding the internal structures of planets with a large H$_2$O component is important for the characterisation of sub-Neptune planets. The finding that the mini-Neptune K2-18b could host a liquid water ocean beneath a mostly hydrogen envelope motivates a detailed examination of the phase structures of water-rich planets. To this end, we present new internal structure models for super-Earths and mini-Neptunes that enable detailed characterisation of a planet's water component. We use our models to explore the possible phase structures of water worlds and find that a diverse range of interiors are possible, from oceans sandwiched between two layers of ice to supercritical interiors beneath steam atmospheres. We determine how the bulk properties and surface conditions of a water world affect its ocean depth, finding that oceans can be up to hundreds of times deeper than on Earth. For example, a planet with a 300 K surface can possess H$_2$O oceans with depths from 30-500 km, depending on its mass and composition. We also constrain the region of mass-radius space in which planets with H/He envelopes could host liquid H$_2$O, noting that the liquid phase can persist at temperatures up to 647 K at high pressures of $218$-$7\times10^4$ bar. Such H/He envelopes could contribute significantly to the planet radius while retaining liquid water at the surface, depending on the planet mass and temperature profile. Our findings highlight the exciting possibility that habitable conditions may be present on planets much larger than Earth.
dc.publisherOxford University Press (OUP)
dc.rightsAttribution 4.0 International
dc.rights.urihttps://creativecommons.org/licenses/by/4.0/
dc.subjectplanets and satellites: composition
dc.subjectplanets and satellites: general
dc.subjectplanets and satellites: interiors
dc.subjectplanets and satellites: oceans
dc.subjectplanets and satellites: surfaces
dc.titleHow deep is the ocean? Exploring the phase structure of water-rich sub-Neptunes
dc.typeArticle
dc.publisher.departmentInstitute of Astronomy
dc.date.updated2022-01-09T07:33:32Z
prism.endingPage3432
prism.issueIdentifier3
prism.publicationDate2021
prism.publicationNameMonthly Notices of the Royal Astronomical Society
prism.startingPage3414
prism.volume505
dc.identifier.doi10.17863/CAM.80053
rioxxterms.versionofrecord10.1093/mnras/stab1500
rioxxterms.versionVoR
dc.contributor.orcidNixon, MC [0000-0001-8236-5553]
dc.contributor.orcidNikku, Madhusudhan [0000-0002-4869-000X]
dc.identifier.eissn1365-2966
dc.publisher.urlhttp://dx.doi.org/10.1093/mnras/stab1500
rioxxterms.typeJournal Article/Review
cam.issuedOnline2021-06-17
cam.depositDate2022-01-09
pubs.licence-identifierapollo-deposit-licence-2-1
pubs.licence-display-nameApollo Repository Deposit Licence Agreement


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Attribution 4.0 International
Except where otherwise noted, this item's licence is described as Attribution 4.0 International