LOFAR observations of a jet-driven piston shock in the low solar corona
Ciara A. Maguire
Abstract
To date, the origin of coronal shocks has been argued as either flare related due to blast<br> waves or CME or small scale ejecta related (Zimovets et al. 2012; Mancuso et al. 2019). Depending<br> on their kinematics, we further classify shocks as either bow shock or piston-driven shock. In this<br> study, I investigated a unique solar event of a plasma jet observed in the EUV and a type II radio burst<br> observed by the LOw-Frequency Array (LOFAR) radio telescope. I used radio interferometric<br> observations from LOFAR to determine the locations of type II fundamental and harmonic emission.<br> The images revealed a clear separation between the fundamental and harmonic sources. This<br> contradicts the underlying plasma emission mechanism according to which the fundamental and<br> harmonic radio waves are generated in the same location and should therefore appear co-spatial. Such behaviour is attributed to radio wave scattering by density inhomogeneities in the<br> corona. Using a model I accounted for radio wave scattering effects and determined the true<br> propagation path of the shock. I then determined where the radio burst was generated in relation to<br> the eruptive structures and the coronal environment that led to shock formation. I showed that the<br> type II burst was generated by a piston shock driven by the jet in the low corona, a case that has<br> rarely been previously studied. This was published in Maguire et al, The Astrophysical Journal (2021).<br>