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2023-04-25 Maximillian Günther (ESTEC)

Habitable(?) Worlds and Stellar Flares

Abstract: Our search for new exoplanets is bringing us closer to habitable worlds than ever before. Especially temperate super-Earths and sub-Neptunes orbiting the coolest stars open unique avenues as prime targets for transit discovery, dynamical mass measurements, and transmission spectroscopy of their atmospheres. However, with an eye on astrobiology, we also need to understand explosive stellar flaring and coronal mass ejections impacting exoplanets. These events can shape and even strip off exoplanet atmospheres, dissociate ozone, and extinguish biology – but they might also trigger prebiotic chemistry and initiate life on the surface. Fortunately, we can now study both exoplanets and flares in one go, leveraging modern surveys like TESS, SPECULOOS, and NGTS, and detailed characterisation with CHEOPS and ASTEP. Here, I will give an extensive overview of recent research highlights connecting exoplanet discovery and atmospheric studies with machine-learning-driven stellar flare detection. I will also include a deeper dive into a peculiar newly discovered class of strongly flaring young red dwarfs; these rapid rotators show complex light curve morphologies that are not yet understood – but may shed a dim light on the “toddler years” of some of the prime targets we investigate for habitability studies to date. Most importantly, I will link these astronomical findings to prebiotic chemistry and ozone sterilisation, identifying which new worlds might lie in a sweet spot for life – and will thus become the prime targets for future atmosphere and biosignature studies with JWST, Ariel, and LUVEX-class missions.