While sunspots are relatively cool and quiescent regions on the Sun, the photosphere around them sometimes erupts with outflows of high energy particles in active regions. Most often these eruptions are in the form of loops and sheets called prominences which remain under the control of the intense magnetic fields associated with solar storms. There are other events which in a matter of minutes can release enormous amounts of energy and eject material out into space. Such violent events are called solar flares.
A core-collapse, or Type II, supernova occurs in massive stars when they can no longer sustain fusion. For most of their lives, stars produce energy by fusing hydrogen into helium. Eventually, the hydrogen runs out and the core contracts until it reaches temperatures hot enough to cause the helium to fuse into carbon. This process repeats through to heavier elements, producing a pre-collapse star with onion-like layers of elements with the heaviest elements near the center. When the core consists mostly of nickel and iron, fusion will come to an end, and the core’s next collapse will trigger the supernova. When astronomers observed Supernova 1987A, the closest supernova in more than 300 years, models predicted that the onion-like layers of the supernova would persist after the explosion. But observations showed core materials reaching the surface much faster than predicting, suggesting that turbulent mixing might be carrying heavier elements outward. The images above show several time steps of a 2D simulation of this type of supernova. In the wake of the expanding shock wave, the core materials form fingers that race outward, mixing the fusion remnants. Hydrodynamically speaking, this is an example of the Richtmyer-Meshkov instability, in which a shock wave generates mixing between fluid layers of differing densities. (Image credit: K. Kifonidis et al.; see also B. Remington)
"TEMPERATURE AND DENSITY vary with height in the Sun’s atmosphere according to these curves. Height in kilometers is shown increasing upward on the scale at left, measured from the top of the photosphere where sunspots are seen. Yellow and orange peaks are chromospheric spicules that jut up into the corona; the transition region between chromosphere and corona is shown as a dark yellow band, only a few hundred kilometers thick, which follows the spicule outlines." Via.