Yesterday’s Astronomy Picture of the Day: a combined visible light/x-ray image of the Cat’s Eye Nebula.
This is a planetary nebula (which has nothing to do with planets). A sun-like star (in the center) is in its dying phase, and is expelling large amounts of extremely hot gas. The purple areas in the center are where the gases are so hot–with temperatures in the millions of degrees–that they emit electromagnetic radiation in the x-ray portion of the spectrum.
Grace and Peace