Multi-threaded prominence oscillations triggered by a coronal shock wave

Abstract

Context. Understanding the interplay between ubiquitous coronal shock waves and the resulting prominence oscillations is a key factor in improving our knowledge of prominences and the solar corona overall. In particular, prominences are a key element of the solar corona and represent a window into an as yet unexplained processes in the Sun’s atmosphere. Aims. To date, most studies on oscillations of prominences have ignored their finer structure and analyzed them strictly as monolithic bodies. In this work, we study the causal relations between a localised energy release and a remote prominence oscillation, where the prominence has a realistic thread-like structure. Methods. In our work, we used an open source magnetohydrodynamic code known as MPI-AMRVAC to create a multi-threaded prominence body. In this domain, we introduced an additional energy source from which a shock wave originates, thereby inducing prominence oscillation. We studied two cases with different source amplitudes to analyze its effect on the oscillations. Results. Our results show that the frequently used pendulum model does not suffice to fully estimate the period of the prominence oscillation, in addition to showing that the influence of the source and the thread-like prominence structure needs to be taken into account. Repeated reflections and transmissions of the initial shock wave occur at the specific locations of multiple high-temperature and high-density gradients in the domain. This includes the left and right transition region located at the footpoints of the magnetic arcade, as well as the various transition regions between the prominence and the corona. This results in numerous interferences of compressional waves propagating within and surrounding the prominence plasma. They contribute to the restoring forces of the oscillation, causing the period to deviate from the expected pendulum model, in addition to leading to differences in attributed damping or even growth in amplitude between the various threads. Along with the global longitudinal motion that result from the shock impact, small-scale transverse oscillations are also evident. Multiple high-frequency oscillations represent the propagation of magnetoacoustic waves. The damping we see is linked to the conversion of energy and its exchange with the surrounding corona. Our simulations demonstrate the exchange of energy between different threads and their different modes of oscillation.