On the Fast Propagating Ultra-hot Disturbance Captured by SDO/AIA: An In-depth Insight into the Coronal Nonlinear Dynamics

The impulsive heating events and their corresponding nonlinear dynamics remain one of the most obscure physical processes in solar atmospheric physics. The complicacy of these processes together with limited observations have greatly hampered our understanding of them. Here, we present, for the first time, an unambiguous example of a nonlinear acoustic wave in a closed coronal loop or loop segment, which appeared as a fast propagating ultra-hot disturbance cohesively in an indistinguishable corona loop with a highly evolving emission intensity profile. Based on the theory of propagating nonlinear waves, we argue that this type of observation can provide further information for the disturbance during its propagation. With this information, we conclude that the propagating nonlinear disturbance can quickly heat the corona through the rarefaction wave, and the disturbance-induced magnetic reconnection should not happen in our observation. Besides, a convenient criterion has also been deduced for the existence of the disturbance-induced reconnection mechanism. All of this provides us with a new insight into the accompanying nonlinear dynamics of solar impulsive heating events, which can not only shed light on problems including coronal heating and the fast formation of hot coronal loops, but also show us a very novel and prospective seismology scheme for the diagnosis of coronal plasma properties.