dc.contributor.author
Luu, Cindy N.
dc.contributor.author
Yu, Xinting
dc.contributor.author
Glein, Christopher R.
dc.contributor.author
Innes, Hamish
dc.contributor.author
Aguichine, Artyom
dc.contributor.author
Krissansen-Totton, Joshua
dc.contributor.author
Moses, Julianne I.
dc.contributor.author
Tsai, Shang-Min
dc.contributor.author
Zhang, Xi
dc.contributor.author
Truong, Ngoc
dc.date.accessioned
2025-02-14T08:06:23Z
dc.date.available
2025-02-14T08:06:23Z
dc.identifier.uri
https://refubium.fu-berlin.de/handle/fub188/46603
dc.identifier.uri
http://dx.doi.org/10.17169/refubium-46317
dc.description.abstract
Temperate exoplanets between the sizes of Earth and Neptune, known as "sub-Neptunes," have emerged as intriguing targets for astrobiology. It is unknown whether these planets resemble Earth-like terrestrial worlds with a habitable surface, Neptune-like giant planets with deep atmospheres and no habitable surface, or something exotic in between. Recent JWST transmission spectroscopy observations of the canonical sub-Neptune, K2-18 b, revealed ~1% CH4, ~1% CO2, and a nondetection of CO in the atmosphere. While previous studies proposed that the observed atmospheric composition could help constrain the lower atmosphere's conditions and determine the interior structure of sub-Neptunes like K2-18 b, the possible interactions between the atmosphere and a hot, supercritical water ocean at its base remain unexplored. In this work, we investigate whether a global supercritical water ocean, resembling a planetary-scale hydrothermal system, can explain these observations on K2-18 b–like sub-Neptunes through equilibrium aqueous geochemical calculations. We find that the observed atmospheric CH4/CO2 ratio implies a minimum ocean temperature of ~710 K, whereas the corresponding CO/CO2 ratio allows ocean temperatures up to ~1070 K. These results indicate that a global supercritical water ocean on K2-18 b is plausible. While life cannot survive in such an ocean, this work represents the first step toward understanding how a global supercritical water ocean may influence observable atmospheric characteristics on volatile-rich sub-Neptunes. Future observations with better-constrained CO and NH3 mixing ratios could further help distinguish between possible interior compositions of K2-18 b.
en
dc.format.extent
12 Seiten
dc.rights.uri
https://creativecommons.org/licenses/by/4.0/
dc.subject
Hydrothermal Worlds
en
dc.subject
Temperate exoplanets
en
dc.subject
Volatile-rich Sub-Neptunes
en
dc.subject.ddc
500 Naturwissenschaften und Mathematik::520 Astronomie::520 Astronomie und zugeordnete Wissenschaften
dc.title
Volatile-rich Sub-Neptunes as Hydrothermal Worlds: The Case of K2-18 b
dc.type
Wissenschaftlicher Artikel
dcterms.bibliographicCitation.articlenumber
L51
dcterms.bibliographicCitation.doi
10.3847/2041-8213/ad9eb1
dcterms.bibliographicCitation.journaltitle
The Astrophysical Journal Letters
dcterms.bibliographicCitation.number
2
dcterms.bibliographicCitation.volume
977
dcterms.bibliographicCitation.url
https://doi.org/10.3847/2041-8213/ad9eb1
refubium.affiliation
Geowissenschaften
refubium.affiliation.other
Institut für Geologische Wissenschaften / Fachrichtung Planetologie und Fernerkundung

refubium.resourceType.isindependentpub
no
dcterms.accessRights.openaire
open access
dcterms.isPartOf.eissn
2041-8213
refubium.resourceType.provider
WoS-Alert