From EUV Brightenings to Stellar Flares: Universal Scaling of Quasi-Periodic Pulsations

Small-scale extreme-ultraviolet (EUV) brightenings are ubiquitous in the solar corona and may represent the low-energy counterparts of larger solar flares, with important implications for coronal heating. A key observational signature of solar and stellar flares is the presence of quasi-periodic pulsations (QPPs), which are thought to reflect fundamental processes of impulsive energy release. QPPs can therefore provide a key diagnostic for determining whether EUV brightenings share the same underlying mechanisms as larger-scale flares or instead represent a fundamentally distinct regime.
Using the high spatial and temporal resolution of the Solar Orbiter/Extreme Ultraviolet Imager, we present the first clear evidence that QPPs are present in EUV brightenings. We characterise their properties over a wide range of spatial and temporal scales and show that their periods extend from a few seconds to several minutes, comparable to those observed in larger flares.

We further demonstrate that the relationship between QPP damping time and period follows a common power-law scaling for both EUV brightenings and EUV solar flares. When combined with previously reported X-ray QPPs from solar and stellar flares, all events align with a single unified scaling trend spanning many orders of magnitude in scale. The universality of this scaling strongly suggests that QPPs in small-scale brightenings, solar flares, and stellar flares are governed by a broadly common underlying physical mechanism.