[astro-ph.SR] Low-mass GKM dwarfs are prime targets for finding habitable-zone Earth-sized planets, but their frequent flares, especially on M~dwarfs, can strongly affect planetary atmospheres through enhanced UV/XUV radiation and stellar proton events, which can drive complex photochemistry and accelerate atmospheric escape.
Current atmospheric and habitability models of planets around low-mass stars often rely on simplified flare inputs, such as fixed-temperature blackbodies or approximate optical-to-UV/XUV conversions.
However, recent observations show that M~dwarfs’ flare temperatures and spectral shapes can vary significantly with flare energy, phase, and stellar type, and that optical-based flare observations may underestimate the flare energy in the UV. Time-resolved spectroscopic flare observations of G- and K-dwarfs also remain rare compared to those of M dwarfs.
Here, we propose that the Nautilus Space Observatory concept can provide a unique opportunity to obtain fast-cadence, precisely flux-calibrated, moderate-resolution NUV-to-NIR spectroscopy of flares across a large sample of GKM dwarfs. These observations will measure the time-dependent flare energy budget from the near-UV/blue continuum to the optical and near-infrared continuum, while resolving key chromospheric lines that trace the underlying flare physics.
We aim to construct a statistical library of empirical flare spectral templates organized by flare and stellar properties, including flare energy, flare phase, and host-star spectral type. This library will provide a practical bridge between observed stellar flare properties and the radiation inputs required for planetary atmospheric evolution and habitability simulations.
Chia-Lung Lin, Adina D. Feinstein, Jeff Valenti, Mark S. Giampapa, Dániel Apai, Julien de Wit, Valeriy Vasilyev, Alexander Shapiro, Prajwal Niraula, Benjamin V. Rackham, Noah Tuchow, Ana Glidden, Nadiia Kostogryz
Comments: 9 pages, 1 figure, 1 table
Subjects: Solar and Stellar Astrophysics (astro-ph.SR); Earth and Planetary Astrophysics (astro-ph.EP); Instrumentation and Methods for Astrophysics (astro-ph.IM)
Cite as: arXiv:2606.26462 [astro-ph.SR] (or arXiv:2606.26462v1 [astro-ph.SR] for this version)
https://doi.org/10.48550/arXiv.2606.26462
Focus to learn more
Submission history
From: Chia-Lung Lin
[v1] Wed, 24 Jun 2026 23:44:27 UTC (7,733 KB)
https://arxiv.org/abs/2606.26462
Astrobiology,
