Nat. Commun. 10, 3504 (2019)

Despite their name, quiet Sun regions harbour a mess of magnetohydrodynamic waves and temperature gradients of millions of degrees. Understanding what drives these gradients between the middle and the upper solar atmosphere has kept solar physicists busy for decades. Jiajia Liu and colleagues have now provided observational evidence of localized swirls in the photosphere generating energy fluxes that reach the upper chromosphere. These may provide a mechanism for supplying heat to the corona.

The team applied an automatic swirl detection algorithm to 765 high-resolution chromospheric intensity maps generated by two telescopes, and identified more than 3,000 swirls. By analysing the temporal correlations between swirls in the different atmospheric layers, they established that photospheric swirls generate Alfvén pulses that propagate upwards, leading, in turn, to chromospheric swirls. The amount of energy channelled upwards and the number of swirls detected are in line with expectations for coronal heating mechanisms.