Solar/Interplanetary radio emissions

Radio emissions occurring in the solar corona and in the interplanetary medium are usually produced by streams of electrons traveling at speeds many times faster than the solar wind velocity. The radio bursts observed by Ulysses fall into two categories -- type II and type III bursts. The former are produced by electrons accelerated at shocks traveling through the solar wind. They typically drift from 1 MHz to 10 kHz in about a day, which corresponds to the motion of the shock waves outward from the Sun. Consequently, the type II burst permits remote tracking of the motion of the shock in the solar wind. The type III bursts result when electrons are accelerated in the low corona, in association with solar flares or other solar activity. These electrons may then stream out from Sun with velocities approaching one-half the speed of light. They produce radio bursts whose drift from high to low frequencies occurs much faster than the type II bursts.

type II burst

type III bursts