A Detailed Polarimetric Imaging Study of Type II Solar Radio Burst with the MWA: Detection of Linear Polarization

Type II radio bursts, produced by magnetohydrodynamic shocks propagating through the solar corona and interplanetary medium, serve as powerful diagnostics of shock properties and ambient coronal magnetic fields. While circular polarization in type II bursts has been extensively studied, most investigations rely on dynamic spectra (DS), providing only spatially integrated measurements. DS obscures spatial variations of the polarization sign and magnitude, potentially causing cancellation effects and misrepresenting true polarization levels. We present a full-polarimetric imaging study of a metric type II burst observed with the Murchison Widefield Array at 78--133 MHz. Remarkably, we report the first detection of linear polarization in a metric type II burst, reaching a polarization fraction of $\sim12\%$ with significant spectro-temporal variability across observing bands. The spectro-temporal, spatial, and morphological properties found in this study establish linear polarization as a new diagnostic of large-scale coronal and interplanetary magnetic field structure through full-Stokes imaging of metric solar radio bursts -- challenging conventional paradigms predicting negligible linear polarization from coherent plasma emission processes.