Space Weather & Heliophysics

Young M Dwarfs Flare Activity Model: Towards Better Exoplanetary Atmospheric Characterisation

By Keith Cowing
Press Release
astro-ph.SR
December 8, 2025
Filed under , , , , , , ,
Young M Dwarfs Flare Activity Model: Towards Better Exoplanetary Atmospheric Characterisation
Surface flux density observed and modelled. The m2F12-37-2.5 (dark green) and cF13-500-3 (light green) stellar atmosphere models are plotted at coefficients Xˆ 1=1 and Xˆ 2 = 1 (the theoretical assumption of the entire stellar surface exhibiting flaring activity). For AU Mic during a flare, the red solid and orange dashed lines show the fitted model spectrum at flare maximum using coefficients from the example fit (the flare data are stated in Table A.1 in Appendix A.2). The inverse H6 model at flare maximum, pre-flare and the ‘fiducial flare’ model from Loyd et al. (2018a) with a comparable ED is plotted as blue dash-dotted, light blue dashed, and purple dashed lines, respectively. Blackbody curves for 3850 K, 6000 K, 8000 K, and 10,000 K are included in black solid, dotted, dash-dotted and dashed lines. The panchromatic AU Mic flux from Feinstein et al. (2022) is plotted in light grey. Insets highlight the FUV (lower left) and TESS (lower right) wavelength ranges. — astro-ph.SR

Context. Stellar flares can significantly influence the atmospheres and habitability of orbiting exoplanets, especially around young and active M dwarfs. Understanding the temporally and spectrally resolved activity of such stars is essential for assessing their impact on planetary environments.

Aims. We aim to examine in detail state-of-the-art concepts of flare models to identify what is missing in our understanding of energy deposition during the flare event. By comparing synthetic and observed flare spectra, we seek to determine the modelling frameworks best suited to represent flare energetics and spectral far-ultraviolet features while providing a foundation for investigating flare impacts on exoplanet atmospheres.

Methods. In this work, we built the Young M Dwarfs Flare (YMDF) model utilising the combination of radiative-hydrodynamic (RHD) stellar atmosphere models with a high and low-energy electron beam and corresponding synthetic observables. These models are based on physical principles and were validated with solar and stellar observations. Results. The newly developed YMDF model reproduces the observed continuum rise in both the TESS photometric band and the FUV-A spectral range. Furthermore, the flare distributions generated within this framework show consistency with those observed in our sample of stars.

Conclusions. We have developed the YMDF model as a tool to reproduce the time-dependent spectra of flaring young M dwarfs, providing a physically motivated description of their spectral and temporal evolution during flare events.

E. Mamonova, A. F. Kowalski, K. Herbst, S. Wedemeyer, S. C. Werner

Subjects: Solar and Stellar Astrophysics (astro-ph.SR); Earth and Planetary Astrophysics (astro-ph.EP)
Cite as: arXiv:2511.23129 [astro-ph.SR](or arXiv:2511.23129v1 [astro-ph.SR] for this version)
https://doi.org/10.48550/arXiv.2511.23129
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Submission history
From: Elena Mamonova
[v1] Fri, 28 Nov 2025 12:21:37 UTC (1,709 KB)
https://arxiv.org/abs/2511.23129

Astrobiology,

Keith Cowing

Explorers Club Fellow, ex-NASA Space Station Payload manager/space biologist, Away Teams, Journalist, Lapsed climber, Synaesthete, Na’Vi-Jedi-Freman-Buddhist-mix, ASL, Devon Island and Everest Base Camp veteran, (he/him) 🖖🏻

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