1 GK Sun
Some fraction of electrons are accelerated to nearly the speed of light
during flares and cause strong radio emission. This figure shows
1992-11-2 flare which occurred on the west limb of the Sun.
The intensity became more than 1 GK (10^9 Kelvin)
in contrast with the solar disk which is 10,000 K.
The total radio flux became 60 times the quiet Sun during this flare.