Linking stellar flares and spots to exoplanet atmospheric escape and photochemistry

Determine how stellar flare and starspot activity on exoplanet host stars drives atmospheric escape and alters photochemical processes within exoplanet atmospheres, specifying the mechanisms and conditions under which these effects occur.

Background

The white paper argues that stellar magnetic activity—manifested through flares, spots, and faculae—can dominate atmospheric chemistry, ionization, and escape in close-in terrestrial planets, particularly around M dwarfs. While photometric surveys have cataloged flares, the lack of time-resolved spectroscopy leaves the translation from stellar activity to atmospheric outcomes poorly constrained.

A next-generation 12-m class facility with integral-field and multi-object spectroscopy is proposed to capture flare spectral energy distributions and chromospheric diagnostics with sufficient cadence to quantify how transient stellar events drive atmospheric escape and photochemistry.

References

Here are the major open questions that the next big telescope developed by ESO will address through conducting a decadal spectroscopic survey of young, active exoplanet hosts: How do flare and spot activity translate into atmospheric escape and photochemistry on exoplanets?

— Transients as Determinants of Habitability  (2512.12456 - Majidi et al., 13 Dec 2025) in Section 3 (Key Questions)