Tracking the motion of a shock along a channel in the low solar corona

Shock waves are excited by coronal mass ejections (CMEs) and large-scale extreme-ultraviolet (EUV) wave fronts and can result in low-frequency radio emission under certain coronal conditions. In this work, we investigate a moving source of low-frequency radio emission as a CME and an associated EUV wave front move along a channel of a lower density, magnetic field, and Alfv \'e n speed in the solar corona. Observations from the Atmospheric Imaging Assembly on board the Solar Dynamics Observatory, the Nançay Radio Heliograph (NRH), and the Irish Low Frequency Array (I-LOFAR) were analysed. Differential emission measure maps were generated to determine densities and Alfv \'e n maps, and the kinematics of the EUV wave front was tracked using CorPITA. The radio sources' positions and velocity were calculated from NRH images and I-LOFAR dynamic spectra. The EUV wave expanded radially with a uniform velocity of sim 500 km s$^ $. However, the radio source was observed to be deflected and appeared to move along a channel of a lower Alfv \'e n speed, abruptly slowing from 1700 km s$^ $ to 250 km s$^ $ as it entered a quiet-Sun region. A shock wave with an apparent radial velocity of $>$ 420 km s$^ $ was determined from the drift rate of the associated Type II radio burst. The apparent motion of the radio source may have resulted from a wave front moving along a coronal wave guide or by different points along the wave front emitting at locations with favourable conditions for shock formation.