Hot Spot Offset Variability from Magnetohydrodynamical Thermoresistive Instability in Hot Jupiters
Hot Jupiter (HJ) atmospheres are possibly subject to a thermoresistive instability (TRI). Such an instability may develop as the ohmic heating increases the electrical conductivity in a positive feedback loop, which ultimately leads to a runaway of the atmospheric temperature. We extend our previous...
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IOP Publishing
2025-01-01
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| Online Access: | https://doi.org/10.3847/1538-4357/ad9902 |
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| author | Raphaël Hardy Paul Charbonneau Andrew Cumming |
| author_facet | Raphaël Hardy Paul Charbonneau Andrew Cumming |
| author_sort | Raphaël Hardy |
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| description | Hot Jupiter (HJ) atmospheres are possibly subject to a thermoresistive instability (TRI). Such an instability may develop as the ohmic heating increases the electrical conductivity in a positive feedback loop, which ultimately leads to a runaway of the atmospheric temperature. We extend our previous axisymmetric one-dimensional radial model, by representing the temperature and magnetic diffusivity as a first-order Fourier expansion in longitude. This allows us to predict the hot spot offset during the rapid unfolding of the TRI and following Alfvénic oscillations. The instability is periodically triggered and damped within ≈10–40 days, depending on the magnetic field strength, with months of slow buildup between recurring bursts. We show a few representative simulations undergoing TRI, in which the peak flux offset varies between approximately ±60 ^∘ on a timescale of a few days with potentially observable brightness variations. Therefore, this TRI could be an observable feature of HJs, given the right timing of observation and transit and the right planetary parameters. |
| format | Article |
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| institution | Kabale University |
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| language | English |
| publishDate | 2025-01-01 |
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| series | The Astrophysical Journal |
| spelling | doaj-art-fad023ea38f046e2a9eaf58321647a5d2025-01-08T06:48:10ZengIOP PublishingThe Astrophysical Journal1538-43572025-01-01978214910.3847/1538-4357/ad9902Hot Spot Offset Variability from Magnetohydrodynamical Thermoresistive Instability in Hot JupitersRaphaël Hardy0https://orcid.org/0000-0002-2599-6225Paul Charbonneau1https://orcid.org/0000-0003-1618-3924Andrew Cumming2https://orcid.org/0000-0002-6335-0169Département de Physique, Université de Montréal , Montréal, QC, H3C 3J7, Canada; Department of Physics and Trottier Space Institute, McGill University , Montréal, QC, H3A 2T8, Canada; Institut Trottier de Recherche sur les Exoplanètes (iREx), Université de Montréal , Montréal, QC, H3C 3J7, CanadaDépartement de Physique, Université de Montréal , Montréal, QC, H3C 3J7, CanadaDepartment of Physics and Trottier Space Institute, McGill University , Montréal, QC, H3A 2T8, Canada; Institut Trottier de Recherche sur les Exoplanètes (iREx), Université de Montréal , Montréal, QC, H3C 3J7, CanadaHot Jupiter (HJ) atmospheres are possibly subject to a thermoresistive instability (TRI). Such an instability may develop as the ohmic heating increases the electrical conductivity in a positive feedback loop, which ultimately leads to a runaway of the atmospheric temperature. We extend our previous axisymmetric one-dimensional radial model, by representing the temperature and magnetic diffusivity as a first-order Fourier expansion in longitude. This allows us to predict the hot spot offset during the rapid unfolding of the TRI and following Alfvénic oscillations. The instability is periodically triggered and damped within ≈10–40 days, depending on the magnetic field strength, with months of slow buildup between recurring bursts. We show a few representative simulations undergoing TRI, in which the peak flux offset varies between approximately ±60 ^∘ on a timescale of a few days with potentially observable brightness variations. Therefore, this TRI could be an observable feature of HJs, given the right timing of observation and transit and the right planetary parameters.https://doi.org/10.3847/1538-4357/ad9902Astrophysical fluid dynamicsMagnetohydrodynamicsExoplanet atmospheric variabilityExoplanet atmospheric dynamicsExoplanet atmospheresAtmospheric dynamics |
| spellingShingle | Raphaël Hardy Paul Charbonneau Andrew Cumming Hot Spot Offset Variability from Magnetohydrodynamical Thermoresistive Instability in Hot Jupiters The Astrophysical Journal Astrophysical fluid dynamics Magnetohydrodynamics Exoplanet atmospheric variability Exoplanet atmospheric dynamics Exoplanet atmospheres Atmospheric dynamics |
| title | Hot Spot Offset Variability from Magnetohydrodynamical Thermoresistive Instability in Hot Jupiters |
| title_full | Hot Spot Offset Variability from Magnetohydrodynamical Thermoresistive Instability in Hot Jupiters |
| title_fullStr | Hot Spot Offset Variability from Magnetohydrodynamical Thermoresistive Instability in Hot Jupiters |
| title_full_unstemmed | Hot Spot Offset Variability from Magnetohydrodynamical Thermoresistive Instability in Hot Jupiters |
| title_short | Hot Spot Offset Variability from Magnetohydrodynamical Thermoresistive Instability in Hot Jupiters |
| title_sort | hot spot offset variability from magnetohydrodynamical thermoresistive instability in hot jupiters |
| topic | Astrophysical fluid dynamics Magnetohydrodynamics Exoplanet atmospheric variability Exoplanet atmospheric dynamics Exoplanet atmospheres Atmospheric dynamics |
| url | https://doi.org/10.3847/1538-4357/ad9902 |
| work_keys_str_mv | AT raphaelhardy hotspotoffsetvariabilityfrommagnetohydrodynamicalthermoresistiveinstabilityinhotjupiters AT paulcharbonneau hotspotoffsetvariabilityfrommagnetohydrodynamicalthermoresistiveinstabilityinhotjupiters AT andrewcumming hotspotoffsetvariabilityfrommagnetohydrodynamicalthermoresistiveinstabilityinhotjupiters |