hot spot
In geology, a hot spot is a center of persistent volcanism, thought to be the surface expression of a rising hot plume of magma in a planetary mantle (as seen, for example, on Earth and on Io). Some hot spots are located on constructive margins, such as Iceland; others occur within plates, for example Hawaii.
In stellar astrophysics, a hot spot is a small, bright region (also known as a bright spot) in a cataclysmic binary, located either where the matter stream collides with the outer edge of the accretion disk, or at the inner edge of the disk.
A small, radio-bright region in a lobe of a radio galaxy, thought to be caused by high-speed material in a jet colliding with boundary between the lobe and the intergalactic medium.