Resistive MHD Simulations of Stellar Wind-Magnetosphere Coupling in TRAPPIST-1e
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| Formato: | Preprint |
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2026
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| author | González-Avilés, J. J. Pérez-Negrón, N. Baltazar Segura, A. |
| author_facet | González-Avilés, J. J. Pérez-Negrón, N. Baltazar Segura, A. |
| contents | Close-in terrestrial exoplanets around M dwarfs reside in dense, magnetized winds, where non-ideal plasma coupling can strongly affect how electromagnetic energy is redistributed within the dayside interaction region. We present three-dimensional resistive magnetohydrodynamic simulations of the TRAPPIST-1 wind interacting with a dipolar TRAPPIST-1e magnetosphere for three stellar-wind forcing cases and four prescribed magnetic diffusivities, $η=(0,\ 538.018,\ 5.38018\times10^{8},\ 5.38018\times10^{12})$ cm$^{2}$ s$^{-1}$. Energy transport is diagnosed using maps of the total energy density, the magnitude of the total Poynting flux, and the divergence of the total Poynting flux. We further estimate a radio-power proxy from the volume integral of $\nabla\cdot \mathbf{S}_{\rm total}$ over the dayside bow-shock and magnetopause layers. Across all cases, increasing prescribed $η$ broadens the coupling layer and shifts the dominant energy-conversion regions from thin, patchy boundary arcs to thicker, more spatially extended structures, with an increasing relative contribution from the magnetopause. The inferred radio-power proxy increases by several orders of magnitude across the explored scan. However, because the estimated numerical magnetic diffusivity in the strongest-gradient regions is $η_{\rm num}\sim10^{15}$-$10^{16}$ cm$^{2}$ s$^{-1}$, the present $η$ scan is best interpreted as a controlled sensitivity study rather than as a direct constraint on the physical diffusivity of the TRAPPIST-1e environment. For the adopted planetary fields ($B_{\rm eq}=0.32$-$1.28$ G), the maximum cyclotron frequencies are $ν_{c,\max}\approx1.8$-$7.2$ MHz, below the ground-based window, implying that meaningful radio constraints on TRAPPIST-1e magnetism will require space-based observations below 10 MHz or substantially stronger planetary fields than those assumed here. |
| format | Preprint |
| id |
arxiv_https___arxiv_org_abs_2604_00191 |
| institution | arXiv |
| publishDate | 2026 |
| record_format | arxiv |
| spellingShingle | Resistive MHD Simulations of Stellar Wind-Magnetosphere Coupling in TRAPPIST-1e González-Avilés, J. J. Pérez-Negrón, N. Baltazar Segura, A. Earth and Planetary Astrophysics Solar and Stellar Astrophysics Close-in terrestrial exoplanets around M dwarfs reside in dense, magnetized winds, where non-ideal plasma coupling can strongly affect how electromagnetic energy is redistributed within the dayside interaction region. We present three-dimensional resistive magnetohydrodynamic simulations of the TRAPPIST-1 wind interacting with a dipolar TRAPPIST-1e magnetosphere for three stellar-wind forcing cases and four prescribed magnetic diffusivities, $η=(0,\ 538.018,\ 5.38018\times10^{8},\ 5.38018\times10^{12})$ cm$^{2}$ s$^{-1}$. Energy transport is diagnosed using maps of the total energy density, the magnitude of the total Poynting flux, and the divergence of the total Poynting flux. We further estimate a radio-power proxy from the volume integral of $\nabla\cdot \mathbf{S}_{\rm total}$ over the dayside bow-shock and magnetopause layers. Across all cases, increasing prescribed $η$ broadens the coupling layer and shifts the dominant energy-conversion regions from thin, patchy boundary arcs to thicker, more spatially extended structures, with an increasing relative contribution from the magnetopause. The inferred radio-power proxy increases by several orders of magnitude across the explored scan. However, because the estimated numerical magnetic diffusivity in the strongest-gradient regions is $η_{\rm num}\sim10^{15}$-$10^{16}$ cm$^{2}$ s$^{-1}$, the present $η$ scan is best interpreted as a controlled sensitivity study rather than as a direct constraint on the physical diffusivity of the TRAPPIST-1e environment. For the adopted planetary fields ($B_{\rm eq}=0.32$-$1.28$ G), the maximum cyclotron frequencies are $ν_{c,\max}\approx1.8$-$7.2$ MHz, below the ground-based window, implying that meaningful radio constraints on TRAPPIST-1e magnetism will require space-based observations below 10 MHz or substantially stronger planetary fields than those assumed here. |
| title | Resistive MHD Simulations of Stellar Wind-Magnetosphere Coupling in TRAPPIST-1e |
| topic | Earth and Planetary Astrophysics Solar and Stellar Astrophysics |
| url | https://arxiv.org/abs/2604.00191 |