Products for "TOI-421 b: A Hot Sub-Neptune with a Haze-Free, Low Mean Molecular Weight Atmosphere"
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Zenodo
2025
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| author | Davenport, Brian Kempton, Eliza Nixon, Matthew Ih, Jegug Deming, Drake Fu, Guangwei May, Erin Bean, Jacob Gao, Peter Rogers, Leslie Malik, Matej |
| author_facet | Davenport, Brian Kempton, Eliza Nixon, Matthew Ih, Jegug Deming, Drake Fu, Guangwei May, Erin Bean, Jacob Gao, Peter Rogers, Leslie Malik, Matej |
| contents | <p>Common features of sub-Neptunes atmospheres observed to date include signatures of aerosols at moderate equilibrium temperatures (~500-800 K), and a prevalence of high mean molecular weight atmospheres, perhaps indicating novel classes of planets such as water worlds. Here we present a 0.83--5 µm JWST transmission spectrum of the sub-Neptune TOI-421 b. This planet is unique among previously observed counterparts in its high equilibrium temperature (Teq ~920 K) and its Sun-like host star. We find marked differences between the atmosphere of TOI-421 b and those of sub-Neptunes previously characterized with JWST, which all orbit late-K and M stars. Specifically, water features in the NIRISS/SOSS bandpass indicate a low mean molecular weight atmosphere consistent with solar metallicity, and no appreciable aerosol coverage. Hints of SO2 and CO but not CO2 or CH4) also exist in our NIRSpec/G395M observations, but not at sufficient signal-to-noise to draw firm conclusions. Our results support a picture in which sub-Neptunes hotter than ~850 K do not form hydrocarbon hazes due to a lack of methane to photolyze. TOI-421 b additionally fits the paradigm of the radius valley for planets orbiting FGK stars being sculpted by mass loss processes, which would leave behind primordial atmospheres overlying rock/iron interiors. Further observations of TOI-421 b and similar hot sub-Neptunes will confirm whether haze-free atmospheres and low mean molecular weights are universal characteristics of such objects.</p> |
| format | Recurso digital |
| id | zenodo_https___doi_org_10_5281_zenodo_15176438 |
| institution | Zenodo |
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| publishDate | 2025 |
| publisher | Zenodo |
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| spellingShingle | Products for "TOI-421 b: A Hot Sub-Neptune with a Haze-Free, Low Mean Molecular Weight Atmosphere" Davenport, Brian Kempton, Eliza Nixon, Matthew Ih, Jegug Deming, Drake Fu, Guangwei May, Erin Bean, Jacob Gao, Peter Rogers, Leslie Malik, Matej <p>Common features of sub-Neptunes atmospheres observed to date include signatures of aerosols at moderate equilibrium temperatures (~500-800 K), and a prevalence of high mean molecular weight atmospheres, perhaps indicating novel classes of planets such as water worlds. Here we present a 0.83--5 µm JWST transmission spectrum of the sub-Neptune TOI-421 b. This planet is unique among previously observed counterparts in its high equilibrium temperature (Teq ~920 K) and its Sun-like host star. We find marked differences between the atmosphere of TOI-421 b and those of sub-Neptunes previously characterized with JWST, which all orbit late-K and M stars. Specifically, water features in the NIRISS/SOSS bandpass indicate a low mean molecular weight atmosphere consistent with solar metallicity, and no appreciable aerosol coverage. Hints of SO2 and CO but not CO2 or CH4) also exist in our NIRSpec/G395M observations, but not at sufficient signal-to-noise to draw firm conclusions. Our results support a picture in which sub-Neptunes hotter than ~850 K do not form hydrocarbon hazes due to a lack of methane to photolyze. TOI-421 b additionally fits the paradigm of the radius valley for planets orbiting FGK stars being sculpted by mass loss processes, which would leave behind primordial atmospheres overlying rock/iron interiors. Further observations of TOI-421 b and similar hot sub-Neptunes will confirm whether haze-free atmospheres and low mean molecular weights are universal characteristics of such objects.</p> |
| title | Products for "TOI-421 b: A Hot Sub-Neptune with a Haze-Free, Low Mean Molecular Weight Atmosphere" |
| url | https://doi.org/10.5281/zenodo.15176438 |