Evidence for a Volcanic Atmosphere on the Sub-Earth L 98-59 b
Assessing the prevalence of atmospheres on rocky planets around M-dwarf stars is a top priority of exoplanet science. High-energy activity from M dwarfs can destroy the atmospheres of these planets, which could explain the lack of atmosphere detections to date. Volcanic outgassing has been proposed...
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IOP Publishing
2025-01-01
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| Series: | The Astrophysical Journal Letters |
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| Online Access: | https://doi.org/10.3847/2041-8213/adaf22 |
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| author | Aaron Bello-Arufe Mario Damiano Katherine A. Bennett Renyu Hu Luis Welbanks Ryan J. MacDonald Darryl Z. Seligman David K. Sing Armen Tokadjian Apurva V. Oza Jeehyun Yang |
| author_facet | Aaron Bello-Arufe Mario Damiano Katherine A. Bennett Renyu Hu Luis Welbanks Ryan J. MacDonald Darryl Z. Seligman David K. Sing Armen Tokadjian Apurva V. Oza Jeehyun Yang |
| author_sort | Aaron Bello-Arufe |
| collection | DOAJ |
| description | Assessing the prevalence of atmospheres on rocky planets around M-dwarf stars is a top priority of exoplanet science. High-energy activity from M dwarfs can destroy the atmospheres of these planets, which could explain the lack of atmosphere detections to date. Volcanic outgassing has been proposed as a mechanism to replenish the atmospheres of tidally heated rocky planets. L 98-59 b, a sub-Earth transiting a nearby M dwarf, was recently identified as the most promising exoplanet to detect a volcanic atmosphere. We present the transmission spectrum of L 98-59 b from four transits observed with JWST NIRSpec G395H. Although the airless model provides an adequate fit to the data based on its χ ^2 , an SO _2 atmosphere is preferred by 3.6 σ over a flat line in terms of the Bayesian evidence. Such an atmosphere would likely be in a steady state where volcanism balances escape. If so, L 98-59 b must experience at least eight times as much volcanism and tidal heating per unit mass as Io. If volcanism is driven by runaway melting of the mantle, we predict the existence of a subsurface magma ocean in L 98-59 b extending up to R _p ∼ 60%–90%. An SO _2 -rich volcanic atmosphere on L 98-59 b would be indicative of an oxidized mantle with an oxygen fugacity of f O _2 > IW + 2.7, and it would imply that L 98-59 b must have retained some of its volatile endowment despite its proximity to its star. Our findings suggest that volcanism may revive secondary atmospheres on tidally heated rocky planets around M dwarfs. |
| format | Article |
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| institution | DOAJ |
| issn | 2041-8205 |
| language | English |
| publishDate | 2025-01-01 |
| publisher | IOP Publishing |
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| series | The Astrophysical Journal Letters |
| spelling | doaj-art-b3121943d45d4fb9818f33d14dd053f42025-08-20T03:17:39ZengIOP PublishingThe Astrophysical Journal Letters2041-82052025-01-019802L2610.3847/2041-8213/adaf22Evidence for a Volcanic Atmosphere on the Sub-Earth L 98-59 bAaron Bello-Arufe0https://orcid.org/0000-0003-3355-1223Mario Damiano1https://orcid.org/0000-0002-1830-8260Katherine A. Bennett2https://orcid.org/0000-0002-9030-0132Renyu Hu3https://orcid.org/0000-0003-2215-8485Luis Welbanks4https://orcid.org/0000-0003-0156-4564Ryan J. MacDonald5https://orcid.org/0000-0003-4816-3469Darryl Z. Seligman6https://orcid.org/0000-0002-0726-6480David K. Sing7https://orcid.org/0000-0001-6050-7645Armen Tokadjian8https://orcid.org/0000-0002-4675-9069Apurva V. Oza9https://orcid.org/0000-0002-1655-0715Jeehyun Yang10https://orcid.org/0000-0002-1551-2610Jet Propulsion Laboratory, California Institute of Technology , Pasadena, CA 91109, USAJet Propulsion Laboratory, California Institute of Technology , Pasadena, CA 91109, USADepartment of Earth & Planetary Sciences, Johns Hopkins University , Baltimore, MD 21218, USAJet Propulsion Laboratory, California Institute of Technology , Pasadena, CA 91109, USA; Division of Geological and Planetary Sciences, California Institute of Technology , Pasadena, CA 91125, USASchool of Earth and Space Exploration, Arizona State University , 781 Terrace Mall, Tempe, AZ 85287, USADepartment of Astronomy, University of Michigan , 1085 S. University Ave., Ann Arbor, MI 48109, USADepartment of Physics and Astronomy, Michigan State University , East Lansing, MI48824, USADepartment of Earth & Planetary Sciences, Johns Hopkins University , Baltimore, MD 21218, USA; Department of Physics & Astronomy, Johns Hopkins University , Baltimore, MD 21218, USAJet Propulsion Laboratory, California Institute of Technology , Pasadena, CA 91109, USAJet Propulsion Laboratory, California Institute of Technology , Pasadena, CA 91109, USA; Division of Geological and Planetary Sciences, California Institute of Technology , Pasadena, CA 91125, USAJet Propulsion Laboratory, California Institute of Technology , Pasadena, CA 91109, USAAssessing the prevalence of atmospheres on rocky planets around M-dwarf stars is a top priority of exoplanet science. High-energy activity from M dwarfs can destroy the atmospheres of these planets, which could explain the lack of atmosphere detections to date. Volcanic outgassing has been proposed as a mechanism to replenish the atmospheres of tidally heated rocky planets. L 98-59 b, a sub-Earth transiting a nearby M dwarf, was recently identified as the most promising exoplanet to detect a volcanic atmosphere. We present the transmission spectrum of L 98-59 b from four transits observed with JWST NIRSpec G395H. Although the airless model provides an adequate fit to the data based on its χ ^2 , an SO _2 atmosphere is preferred by 3.6 σ over a flat line in terms of the Bayesian evidence. Such an atmosphere would likely be in a steady state where volcanism balances escape. If so, L 98-59 b must experience at least eight times as much volcanism and tidal heating per unit mass as Io. If volcanism is driven by runaway melting of the mantle, we predict the existence of a subsurface magma ocean in L 98-59 b extending up to R _p ∼ 60%–90%. An SO _2 -rich volcanic atmosphere on L 98-59 b would be indicative of an oxidized mantle with an oxygen fugacity of f O _2 > IW + 2.7, and it would imply that L 98-59 b must have retained some of its volatile endowment despite its proximity to its star. Our findings suggest that volcanism may revive secondary atmospheres on tidally heated rocky planets around M dwarfs.https://doi.org/10.3847/2041-8213/adaf22Exoplanet atmospheric compositionVolcanismExtrasolar rocky planetsJames Webb Space TelescopeTransmission spectroscopy |
| spellingShingle | Aaron Bello-Arufe Mario Damiano Katherine A. Bennett Renyu Hu Luis Welbanks Ryan J. MacDonald Darryl Z. Seligman David K. Sing Armen Tokadjian Apurva V. Oza Jeehyun Yang Evidence for a Volcanic Atmosphere on the Sub-Earth L 98-59 b The Astrophysical Journal Letters Exoplanet atmospheric composition Volcanism Extrasolar rocky planets James Webb Space Telescope Transmission spectroscopy |
| title | Evidence for a Volcanic Atmosphere on the Sub-Earth L 98-59 b |
| title_full | Evidence for a Volcanic Atmosphere on the Sub-Earth L 98-59 b |
| title_fullStr | Evidence for a Volcanic Atmosphere on the Sub-Earth L 98-59 b |
| title_full_unstemmed | Evidence for a Volcanic Atmosphere on the Sub-Earth L 98-59 b |
| title_short | Evidence for a Volcanic Atmosphere on the Sub-Earth L 98-59 b |
| title_sort | evidence for a volcanic atmosphere on the sub earth l 98 59 b |
| topic | Exoplanet atmospheric composition Volcanism Extrasolar rocky planets James Webb Space Telescope Transmission spectroscopy |
| url | https://doi.org/10.3847/2041-8213/adaf22 |
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