The Fate of Oceans on First-generation Planets Orbiting White Dwarfs
Several groups have recently suggested that small planets orbiting very closely around white dwarf stars could be promising locations for life to arise, even after stellar death. There are still many uncertainties, however, regarding the existence and habitability of these worlds. Here we consider t...
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IOP Publishing
2025-01-01
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| author | Juliette Becker Andrew Vanderburg Joseph R. Livesey |
| author_facet | Juliette Becker Andrew Vanderburg Joseph R. Livesey |
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| description | Several groups have recently suggested that small planets orbiting very closely around white dwarf stars could be promising locations for life to arise, even after stellar death. There are still many uncertainties, however, regarding the existence and habitability of these worlds. Here we consider the retention of water during post-main-sequence evolution of a Sun-like star and during the subsequent migration of planets to the white dwarf's habitable zone. This inward migration is driven by dynamical mechanisms such as planet–planet interactions in packed systems, which can excite planets to high eccentricities, setting the initial conditions for tidal migration into short-period orbits. In order for water to persist on the surfaces of planets orbiting white dwarfs, the water must first survive the asymptotic giant branch phase of stellar evolution, then avoid being lost as a result of photoevaporation due to X-ray and extreme-ultraviolet radiation from the newly formed white dwarf, and finally survive the tidal migration of the planet inward to the habitable zone. We find that while this journey will likely desiccate large swaths of post-main-sequence planetary systems, planets with substantial reservoirs of water may retain some surface water, especially if their migration occurs at later white dwarf cooling ages. Therefore, although stellar evolution may pose a challenge for the retention of water on exoplanet surfaces, it is possible for planets to retain surface oceans even as their host stars die and their orbits evolve. |
| format | Article |
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| spelling | doaj-art-5fcecf307e5548fc82e54d5eb8e23c3e2025-08-20T02:25:44ZengIOP PublishingThe Astrophysical Journal1538-43572025-01-0197929910.3847/1538-4357/ada149The Fate of Oceans on First-generation Planets Orbiting White DwarfsJuliette Becker0https://orcid.org/0000-0002-7733-4522Andrew Vanderburg1https://orcid.org/0000-0001-7246-5438Joseph R. Livesey2https://orcid.org/0000-0003-3888-3753Department of Astronomy, University of Wisconsin –Madison, 475 N. Charter Street, Madison, WI 53706, USA ; juliette.becker@wisc.eduDepartment of Physics and Kavli Institute for Astrophysics and Space Research, Massachusetts Institute of Technology , Cambridge, MA 02139, USADepartment of Astronomy, University of Wisconsin –Madison, 475 N. Charter Street, Madison, WI 53706, USA ; juliette.becker@wisc.eduSeveral groups have recently suggested that small planets orbiting very closely around white dwarf stars could be promising locations for life to arise, even after stellar death. There are still many uncertainties, however, regarding the existence and habitability of these worlds. Here we consider the retention of water during post-main-sequence evolution of a Sun-like star and during the subsequent migration of planets to the white dwarf's habitable zone. This inward migration is driven by dynamical mechanisms such as planet–planet interactions in packed systems, which can excite planets to high eccentricities, setting the initial conditions for tidal migration into short-period orbits. In order for water to persist on the surfaces of planets orbiting white dwarfs, the water must first survive the asymptotic giant branch phase of stellar evolution, then avoid being lost as a result of photoevaporation due to X-ray and extreme-ultraviolet radiation from the newly formed white dwarf, and finally survive the tidal migration of the planet inward to the habitable zone. We find that while this journey will likely desiccate large swaths of post-main-sequence planetary systems, planets with substantial reservoirs of water may retain some surface water, especially if their migration occurs at later white dwarf cooling ages. Therefore, although stellar evolution may pose a challenge for the retention of water on exoplanet surfaces, it is possible for planets to retain surface oceans even as their host stars die and their orbits evolve.https://doi.org/10.3847/1538-4357/ada149Exoplanet astronomyHabitable zoneWhite dwarf stars |
| spellingShingle | Juliette Becker Andrew Vanderburg Joseph R. Livesey The Fate of Oceans on First-generation Planets Orbiting White Dwarfs The Astrophysical Journal Exoplanet astronomy Habitable zone White dwarf stars |
| title | The Fate of Oceans on First-generation Planets Orbiting White Dwarfs |
| title_full | The Fate of Oceans on First-generation Planets Orbiting White Dwarfs |
| title_fullStr | The Fate of Oceans on First-generation Planets Orbiting White Dwarfs |
| title_full_unstemmed | The Fate of Oceans on First-generation Planets Orbiting White Dwarfs |
| title_short | The Fate of Oceans on First-generation Planets Orbiting White Dwarfs |
| title_sort | fate of oceans on first generation planets orbiting white dwarfs |
| topic | Exoplanet astronomy Habitable zone White dwarf stars |
| url | https://doi.org/10.3847/1538-4357/ada149 |
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