Confined pseudo-shocks as an energy source for the active solar corona

The Sun’s active corona requires an energy flux of ~10³ W m⁻² to compensate for radiative losses and to maintain its high temperature¹. Plasma moves in the corona through magnetic loops^2,3, which may be connected with the flows in and around sunspots^4–6. Global energizing processes (for example, reconnection) play an important part in heating the corona^7–9; however, energy and mass transport may also occur via shocks, waves or flows^5,10,11. A full picture and the influence of such localized events, which significantly couple with various layers of the solar upper atmosphere, is still not clear. Using the Interface Region Imaging Spectrograph temporal image data of C ii 1,330 Å, we observed the presence of pseudo-shocks around a sunspot. Unlike shocks¹², pseudo-shocks exhibit discontinuities only in the mass density. A two-fluid numerical simulation reproduces such confined pseudo-shocks with rarefied plasma regions lagging behind them. We find that these pseudo-shocks carry an energy of ~10³ W m⁻², which is enough to locally power the inner corona and also generate bulk flows (~10⁻⁵ kg m⁻² s⁻¹), contributing to the localized mass transport. If they are ubiquitous, such energized and bulky pseudo-shocks above active regions could provide an important contribution to the heating and mass transport in the overlying solar corona.