Ab Initio Entropy Calculations of Water Predict the Interiors of Uranus and Neptune to Be 15%–30% Colder than Previous Models
Ab initio free energy calculations are employed to derive the entropy of liquid and superionic water over a wide range of conditions in the interiors of Uranus and Neptune. The resulting adiabats are much shallower in pressure–temperature space than those adopted for earlier models of Uranus and Nep...
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IOP Publishing
2025-01-01
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| Series: | The Astrophysical Journal |
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| Online Access: | https://doi.org/10.3847/1538-4357/adef48 |
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| author | Burkhard Militzer |
| author_facet | Burkhard Militzer |
| author_sort | Burkhard Militzer |
| collection | DOAJ |
| description | Ab initio free energy calculations are employed to derive the entropy of liquid and superionic water over a wide range of conditions in the interiors of Uranus and Neptune. The resulting adiabats are much shallower in pressure–temperature space than those adopted for earlier models of Uranus and Neptune. Our models for their interiors are thus much colder, increasing the likelihood that diamond rain or the recently predicted phase separation of planetary ices has occurred in the mantles of ice giant planets. Based on our ab initio data, we construct interior models for Uranus and Neptune with the concentric MacLaurin spheroid method that match the existing gravity measurements. We compare fully convective models with models that include a convective boundary between liquid and superionic water. We also share a code to characterize giant planet atmospheres where para- and ortho-hydrogen as well as helium are present. |
| format | Article |
| id | doaj-art-b9617e9fe2ef4b93bcbdbbf6525e6d8e |
| institution | Kabale University |
| issn | 1538-4357 |
| language | English |
| publishDate | 2025-01-01 |
| publisher | IOP Publishing |
| record_format | Article |
| series | The Astrophysical Journal |
| spelling | doaj-art-b9617e9fe2ef4b93bcbdbbf6525e6d8e2025-08-22T06:19:22ZengIOP PublishingThe Astrophysical Journal1538-43572025-01-0199012010.3847/1538-4357/adef48Ab Initio Entropy Calculations of Water Predict the Interiors of Uranus and Neptune to Be 15%–30% Colder than Previous ModelsBurkhard Militzer0https://orcid.org/0000-0002-7092-5629Department of Earth and Planetary Science, Department of Astronomy, University of California , Berkeley, CA 94720, USAAb initio free energy calculations are employed to derive the entropy of liquid and superionic water over a wide range of conditions in the interiors of Uranus and Neptune. The resulting adiabats are much shallower in pressure–temperature space than those adopted for earlier models of Uranus and Neptune. Our models for their interiors are thus much colder, increasing the likelihood that diamond rain or the recently predicted phase separation of planetary ices has occurred in the mantles of ice giant planets. Based on our ab initio data, we construct interior models for Uranus and Neptune with the concentric MacLaurin spheroid method that match the existing gravity measurements. We compare fully convective models with models that include a convective boundary between liquid and superionic water. We also share a code to characterize giant planet atmospheres where para- and ortho-hydrogen as well as helium are present.https://doi.org/10.3847/1538-4357/adef48UranusNeptuneSolar system planetsExtrasolar ice giantsPlanetary interior |
| spellingShingle | Burkhard Militzer Ab Initio Entropy Calculations of Water Predict the Interiors of Uranus and Neptune to Be 15%–30% Colder than Previous Models The Astrophysical Journal Uranus Neptune Solar system planets Extrasolar ice giants Planetary interior |
| title | Ab Initio Entropy Calculations of Water Predict the Interiors of Uranus and Neptune to Be 15%–30% Colder than Previous Models |
| title_full | Ab Initio Entropy Calculations of Water Predict the Interiors of Uranus and Neptune to Be 15%–30% Colder than Previous Models |
| title_fullStr | Ab Initio Entropy Calculations of Water Predict the Interiors of Uranus and Neptune to Be 15%–30% Colder than Previous Models |
| title_full_unstemmed | Ab Initio Entropy Calculations of Water Predict the Interiors of Uranus and Neptune to Be 15%–30% Colder than Previous Models |
| title_short | Ab Initio Entropy Calculations of Water Predict the Interiors of Uranus and Neptune to Be 15%–30% Colder than Previous Models |
| title_sort | ab initio entropy calculations of water predict the interiors of uranus and neptune to be 15 30 colder than previous models |
| topic | Uranus Neptune Solar system planets Extrasolar ice giants Planetary interior |
| url | https://doi.org/10.3847/1538-4357/adef48 |
| work_keys_str_mv | AT burkhardmilitzer abinitioentropycalculationsofwaterpredicttheinteriorsofuranusandneptunetobe1530colderthanpreviousmodels |