Large- and small-scale magnetic activity driving microwave polar brightening in the Sun

Researchers from institutions including the Aryabhatta Research Institute of Observational Sciences (ARIES), Udaipur Solar Observatory (USO)/PRL, IIT Delhi, and IIT Roorkee have investigated the cause of microwave polar brightening in the Sun using nearly three decades of observations from the Nobeyama Radioheliograph. By combining radio data with NASA's Solar Dynamics Observatory extreme-ultraviolet observations and Wilcox Solar Observatory magnetic field measurements, the study revealed that microwave polar brightening is strongly related to polar coronal hole size and polar magnetic field strength. Furthermore, localized bright patches were found to coincide with coronal bright points and coronal jets, indicating that both large-scale and small-scale magnetic processes drive the phenomenon.