Similarities and differences between solar and stellar flare pulsation processes

Quasi-periodic pulsations (QPPs) are oscillatory signatures commonly detected in the light curves of solar and stellar flares, offering valuable diagnostics of the underlying magnetic and plasma processes. This review compares the observational characteristics, detection methods and physical interpretations of QPPs in both solar and stellar contexts. Solar flare QPPs, extensively studied in X-rays and extreme-UV (EUV) bands using instruments such as Geostationary Operational Environmental Satellite (GOES), Spectrometer Telescope for Imaging X-rays (STIX) on-board Solar Orbiter and Fermi, display typical periods of tens of seconds and show correlations with flare duration and magnetic loop length. Stellar QPPs, observed in X-rays and white light by missions such as Kepler, Transiting Exoplanet Survey Satellite (TESS) and XMM-Newton, exhibit much longer periods-ranging from minutes to hours-consistent with larger-scale magnetic structures in more active stars. Despite differences in scale and observing band, statistical and comparative studies reveal common scaling relations and damping behaviours, suggesting that both solar and stellar QPPs are manifestations of the same fundamental mechanisms, probably magnetohydrodynamic (MHD) oscillations or oscillatory reconnection within flare loops. The comparison underscores a continuity between solar and stellar magnetic activity, linking the solar detailed physical processes to stellar-scale phenomena and providing constraints for future models and surveys. This article is part of the theme issue 'Transferable mechanisms in the oscillatory processes of solar and stellar flares'.