Helium in the Extended Atmosphere of the Warm Super-Puff TOI-1420b
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arXiv
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| Natura: | Preprint |
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2024
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| author | Vissapragada, Shreyas Greklek-McKeon, Michael Linssen, Dion MacLeod, Morgan Thorngren, Daniel P. Gao, Peter Knutson, Heather A. Latham, David W. López-Morales, Mercedes Oklopčić, Antonija González, Jorge Pérez Saidel, Morgan Tumborang, Abigail Yoshida, Stephanie |
| author_facet | Vissapragada, Shreyas Greklek-McKeon, Michael Linssen, Dion MacLeod, Morgan Thorngren, Daniel P. Gao, Peter Knutson, Heather A. Latham, David W. López-Morales, Mercedes Oklopčić, Antonija González, Jorge Pérez Saidel, Morgan Tumborang, Abigail Yoshida, Stephanie |
| contents | Super-puffs are planets with exceptionally low densities ($ρ\lesssim 0.1$~g~cm$^{-3}$) and core masses ($M_c \lesssim 5 M_\oplus$). Many lower-mass ($M_p\lesssim10M_\oplus$) super-puffs are expected to be unstable to catastrophic mass loss via photoevaporation and/or boil-off, whereas the larger gravitational potentials of higher-mass ($M_p\gtrsim10M_\oplus$) super-puffs should make them more stable to these processes. We test this expectation by studying atmospheric loss in the warm, higher-mass super-puff TOI-1420b ($M = 25.1M_\oplus$, $R = 11.9R_\oplus$, $ρ= 0.08$~g~cm$^{-3}$, $T_\mathrm{eq} = 960$~K). We observed one full transit and one partial transit of this planet using the metastable helium filter on Palomar/WIRC and found that the helium transits were $0.671\pm0.079\%$ (8.5$σ$) deeper than the TESS transits, indicating an outflowing atmosphere. We modeled the excess helium absorption using a self-consistent 1D hydrodynamics code to constrain the thermal structure of the outflow given different assumptions for the stellar XUV spectrum. These calculations then informed a 3D simulation which provided a good match to the observations with a modest planetary mass-loss rate of $10^{10.82}$~g~s$^{-1}$ ($M_p/\dot{M}\approx70$~Gyr). Super-puffs with $M_p\gtrsim10M_\oplus$, like TOI-1420b and WASP-107b, appear perfectly capable of retaining atmospheres over long timescales; therefore, these planets may have formed with the unusually large envelope mass fractions they appear to possess today. Alternatively, tidal circularization could have plausibly heated and inflated these planets, which would bring their envelope mass fractions into better agreement with expectations from core-nucleated accretion. |
| format | Preprint |
| id |
arxiv_https___arxiv_org_abs_2403_05614 |
| institution | arXiv |
| publishDate | 2024 |
| record_format | arxiv |
| spellingShingle | Helium in the Extended Atmosphere of the Warm Super-Puff TOI-1420b Vissapragada, Shreyas Greklek-McKeon, Michael Linssen, Dion MacLeod, Morgan Thorngren, Daniel P. Gao, Peter Knutson, Heather A. Latham, David W. López-Morales, Mercedes Oklopčić, Antonija González, Jorge Pérez Saidel, Morgan Tumborang, Abigail Yoshida, Stephanie Earth and Planetary Astrophysics Super-puffs are planets with exceptionally low densities ($ρ\lesssim 0.1$~g~cm$^{-3}$) and core masses ($M_c \lesssim 5 M_\oplus$). Many lower-mass ($M_p\lesssim10M_\oplus$) super-puffs are expected to be unstable to catastrophic mass loss via photoevaporation and/or boil-off, whereas the larger gravitational potentials of higher-mass ($M_p\gtrsim10M_\oplus$) super-puffs should make them more stable to these processes. We test this expectation by studying atmospheric loss in the warm, higher-mass super-puff TOI-1420b ($M = 25.1M_\oplus$, $R = 11.9R_\oplus$, $ρ= 0.08$~g~cm$^{-3}$, $T_\mathrm{eq} = 960$~K). We observed one full transit and one partial transit of this planet using the metastable helium filter on Palomar/WIRC and found that the helium transits were $0.671\pm0.079\%$ (8.5$σ$) deeper than the TESS transits, indicating an outflowing atmosphere. We modeled the excess helium absorption using a self-consistent 1D hydrodynamics code to constrain the thermal structure of the outflow given different assumptions for the stellar XUV spectrum. These calculations then informed a 3D simulation which provided a good match to the observations with a modest planetary mass-loss rate of $10^{10.82}$~g~s$^{-1}$ ($M_p/\dot{M}\approx70$~Gyr). Super-puffs with $M_p\gtrsim10M_\oplus$, like TOI-1420b and WASP-107b, appear perfectly capable of retaining atmospheres over long timescales; therefore, these planets may have formed with the unusually large envelope mass fractions they appear to possess today. Alternatively, tidal circularization could have plausibly heated and inflated these planets, which would bring their envelope mass fractions into better agreement with expectations from core-nucleated accretion. |
| title | Helium in the Extended Atmosphere of the Warm Super-Puff TOI-1420b |
| topic | Earth and Planetary Astrophysics |
| url | https://arxiv.org/abs/2403.05614 |