Evolution of spots and faculae and their bias on exoplanet measurements

Determine how starspots and faculae evolve on exoplanet host stars and quantify the biases they introduce into exoplanet measurements, including transit and spectroscopic observations.

Background

Stellar heterogeneity from spots and faculae can imprint signals at or above the precision required for atmospheric characterization, affecting transmission spectra and photometry.

Time-resolved spectra and line-profile tomography enabled by multiplexed, high-resolution observations are necessary to track surface features and correct biases in exoplanet data.

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 spots and faculae evolve, and how do they bias exoplanet measurements?

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