Proton Irradiation of Primitive Atmospheres of Young Exoplanets And Early Earth: N2O Greenhouse Warming And Prebiotic Synthesis
The emergence of habitable conditions on the early Earth and on rocky exoplanets requires persistent energy sources that can drive both prebiotic chemistry and climate warming under magnetically active young G to M stars.
To quantify the contribution of stellar energetic particle (StEP) events associated with superflares to the atmospheric chemistry of young planets with primitive atmospheres, we carried out a suite of laboratory proton irradiation experiments on mildly reduced gas mixtures.
We present first proton irradiation experiments of N2O/CO2 rich gas mixtures that yield abundant nitrous oxide (N2O) at mixing ratios up to 1000 ppmv, together with amino acid precursors including glycine, corresponding to global production rates of order 2×1010 kg/yr on the early Earth. Our photochemical modeling of StEP driven proton irradiation reproduces the experimentally inferred N2O production rates and provides self-consistent atmospheric N2O profiles.
We then use these profiles of N2O as input to a 3D global climate model to evaluate the radiative and climatic impact of StEP generated N2O in primitive atmospheres representative of the early Earth and young rocky exoplanets. Our results show that frequent StEP events can help alleviate the faint young Sun paradox on the early Earth and can maintain temperate surface conditions on young rocky exoplanets beyond the outer edges of habitable zone, while simultaneously enhancing the buildup of prebiotic molecules.
Together, these processes may constitute a robust pathway toward early planetary habitability.
Kensei Kobayashi, Vladimir S. Airapetian, Takumi Udo, Shunsuke Mouri, Yoko Kebukawa, Hitoshi Fukuda, Yoshiyuki Oguri, Naoto Hagura, M.J. Way, Guillaume Gronoff, Eric T. Wolf
Comments: Accepted by Astrophysical Journal Letters, 15 pages, 5 figures, 2 tables
Subjects: Earth and Planetary Astrophysics (astro-ph.EP); Instrumentation and Methods for Astrophysics (astro-ph.IM); Solar and Stellar Astrophysics (astro-ph.SR)
Cite as: arXiv:2603.18206 [astro-ph.EP] (or arXiv:2603.18206v1 [astro-ph.EP] for this version)
https://doi.org/10.48550/arXiv.2603.18206
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Submission history
From: Vladimir Airapetian
[v1] Wed, 18 Mar 2026 18:56:27 UTC (602 KB)
https://arxiv.org/abs/2603.18206
Astrobiology,
