Atmospheric Mass Loss from TOI-1259 A b, a Gas Giant Planet with a White Dwarf Companion
The lack of close-in Neptune-mass exoplanets evident in transit surveys has largely been attributed to either photoevaporative mass loss or high-eccentricity migration. To distinguish between these two possibilities, we investigate the origins of TOI-1259 A b, a Saturn-mass (0.4 M _J , 1.0 R _J ) ex...
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IOP Publishing
2025-01-01
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| Online Access: | https://doi.org/10.3847/1538-3881/ada49f |
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| author | Morgan Saidel Shreyas Vissapragada Jessica Spake Heather A. Knutson Dion Linssen Michael Zhang Michael Greklek-McKeon Jorge Pérez-González Antonija Oklopčić |
| author_facet | Morgan Saidel Shreyas Vissapragada Jessica Spake Heather A. Knutson Dion Linssen Michael Zhang Michael Greklek-McKeon Jorge Pérez-González Antonija Oklopčić |
| author_sort | Morgan Saidel |
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| description | The lack of close-in Neptune-mass exoplanets evident in transit surveys has largely been attributed to either photoevaporative mass loss or high-eccentricity migration. To distinguish between these two possibilities, we investigate the origins of TOI-1259 A b, a Saturn-mass (0.4 M _J , 1.0 R _J ) exoplanet lying along the upper edge of the Neptune desert. TOI-1259 A b's close-in ( P = 3.48 days) orbit and low bulk density make the planet particularly vulnerable to photoevaporation. We studied the upper atmosphere of TOI-1259 A b using metastable helium 1083 nm transits observed with Palomar/WIRC and Keck/NIRSPEC. We report a band-integrated excess absorption of 0.395% ± 0.072% with Palomar/WIRC and a spectroscopically resolved 5.5 ± 0.94 km s ^−1 blueshifted absorption of 2.4% ± 0.52% ( T _1 – T _4 ) and 3.5% ± 0.72% ( T _2 – T _3 ) with Keck/NIRSPEC. These measurements indicate the presence of an extended escaping atmosphere. Fitting these signals with a Parker wind model, we determine a corresponding atmospheric mass-loss rate of log( $\dot{M}$ ) = 10.2–10.65 g s ^−1 for thermosphere temperatures between 7900 and 8600 K. This relatively low rate suggests that this planet would not have been significantly altered by mass loss even if it formed in situ. However, the presence of a white dwarf companion, TOI-1259 B, hints that this planet may not have formed close-in, but rather migrated inward relatively late. Given the estimated parameters of the proto−white dwarf companion, we find that high-eccentricity migration is possible for the system. |
| format | Article |
| id | doaj-art-83950b47f71848d1a23e2b614bce8a75 |
| institution | OA Journals |
| issn | 1538-3881 |
| language | English |
| publishDate | 2025-01-01 |
| publisher | IOP Publishing |
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| series | The Astronomical Journal |
| spelling | doaj-art-83950b47f71848d1a23e2b614bce8a752025-08-20T02:08:15ZengIOP PublishingThe Astronomical Journal1538-38812025-01-01169210410.3847/1538-3881/ada49fAtmospheric Mass Loss from TOI-1259 A b, a Gas Giant Planet with a White Dwarf CompanionMorgan Saidel0https://orcid.org/0000-0001-9518-9691Shreyas Vissapragada1https://orcid.org/0000-0003-2527-1475Jessica Spake2https://orcid.org/0000-0002-5547-3775Heather A. Knutson3https://orcid.org/0000-0002-5375-4725Dion Linssen4https://orcid.org/0000-0001-6025-6663Michael Zhang5https://orcid.org/0000-0002-0659-1783Michael Greklek-McKeon6https://orcid.org/0000-0002-0371-1647Jorge Pérez-González7https://orcid.org/0000-0001-7144-589XAntonija Oklopčić8https://orcid.org/0000-0002-9584-6476Division of Geological and Planetary Sciences, California Institute of Technology , Pasadena, CA 91125, USA ; msaidel@caltech.eduCarnegie Science Observatories , 813 Santa Barbara Street, Pasadena, CA 91101, USACarnegie Science Observatories , 813 Santa Barbara Street, Pasadena, CA 91101, USADivision of Geological and Planetary Sciences, California Institute of Technology , Pasadena, CA 91125, USA ; msaidel@caltech.eduAnton Pannekoek Institute of Astronomy, University of Amsterdam , Science Park 904, 1098 XH Amsterdam, The NetherlandsDepartment of Astronomy & Astrophysics, University of Chicago , Chicago, IL 60637, USADivision of Geological and Planetary Sciences, California Institute of Technology , Pasadena, CA 91125, USA ; msaidel@caltech.eduDepartment of Physics and Astronomy, University College London , Gower Street, WC1E 6BT London, UKAnton Pannekoek Institute of Astronomy, University of Amsterdam , Science Park 904, 1098 XH Amsterdam, The NetherlandsThe lack of close-in Neptune-mass exoplanets evident in transit surveys has largely been attributed to either photoevaporative mass loss or high-eccentricity migration. To distinguish between these two possibilities, we investigate the origins of TOI-1259 A b, a Saturn-mass (0.4 M _J , 1.0 R _J ) exoplanet lying along the upper edge of the Neptune desert. TOI-1259 A b's close-in ( P = 3.48 days) orbit and low bulk density make the planet particularly vulnerable to photoevaporation. We studied the upper atmosphere of TOI-1259 A b using metastable helium 1083 nm transits observed with Palomar/WIRC and Keck/NIRSPEC. We report a band-integrated excess absorption of 0.395% ± 0.072% with Palomar/WIRC and a spectroscopically resolved 5.5 ± 0.94 km s ^−1 blueshifted absorption of 2.4% ± 0.52% ( T _1 – T _4 ) and 3.5% ± 0.72% ( T _2 – T _3 ) with Keck/NIRSPEC. These measurements indicate the presence of an extended escaping atmosphere. Fitting these signals with a Parker wind model, we determine a corresponding atmospheric mass-loss rate of log( $\dot{M}$ ) = 10.2–10.65 g s ^−1 for thermosphere temperatures between 7900 and 8600 K. This relatively low rate suggests that this planet would not have been significantly altered by mass loss even if it formed in situ. However, the presence of a white dwarf companion, TOI-1259 B, hints that this planet may not have formed close-in, but rather migrated inward relatively late. Given the estimated parameters of the proto−white dwarf companion, we find that high-eccentricity migration is possible for the system.https://doi.org/10.3847/1538-3881/ada49fExoplanet evolutionExoplanetsExoplanet atmospheresExoplanet astronomyPlanetary atmospheresExtrasolar gaseous planets |
| spellingShingle | Morgan Saidel Shreyas Vissapragada Jessica Spake Heather A. Knutson Dion Linssen Michael Zhang Michael Greklek-McKeon Jorge Pérez-González Antonija Oklopčić Atmospheric Mass Loss from TOI-1259 A b, a Gas Giant Planet with a White Dwarf Companion The Astronomical Journal Exoplanet evolution Exoplanets Exoplanet atmospheres Exoplanet astronomy Planetary atmospheres Extrasolar gaseous planets |
| title | Atmospheric Mass Loss from TOI-1259 A b, a Gas Giant Planet with a White Dwarf Companion |
| title_full | Atmospheric Mass Loss from TOI-1259 A b, a Gas Giant Planet with a White Dwarf Companion |
| title_fullStr | Atmospheric Mass Loss from TOI-1259 A b, a Gas Giant Planet with a White Dwarf Companion |
| title_full_unstemmed | Atmospheric Mass Loss from TOI-1259 A b, a Gas Giant Planet with a White Dwarf Companion |
| title_short | Atmospheric Mass Loss from TOI-1259 A b, a Gas Giant Planet with a White Dwarf Companion |
| title_sort | atmospheric mass loss from toi 1259 a b a gas giant planet with a white dwarf companion |
| topic | Exoplanet evolution Exoplanets Exoplanet atmospheres Exoplanet astronomy Planetary atmospheres Extrasolar gaseous planets |
| url | https://doi.org/10.3847/1538-3881/ada49f |
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