The first mission I worked on a Goddard Space Flight Center was the UV and X-ray astronomy satellite called Swift. These Swift Ultraviolet optical telescope images show a galaxy called M82 before and after a supernova. The pre-explosion view combines data taken between 2007 and 2013. The view showing SN 2014J (arrow) merges three exposures taken on 22 January, 2014. Mid-ultraviolet light is shown in blue, near-UV light in green, and visible light in red. The image is slightly more than half the apparent diameter of a full moon across.
This was a Type Ia supernova, the total destruction of a white dwarf star by one of two possible scenarios. In one, the white dwarf orbits a normal star, pulls a stream of matter from it, and gains mass until it reaches a critical threshold and explodes. In the other, the blast arises when two white dwarfs in a binary system eventually spiral inward and collide.
In either case, the star-shattering kaboom produces a superheated shell of plasma that expands outward into space at tens of millions of miles an hour.
M82 (aka the Cigar Galaxy) is located in the constellation Ursa Major and is a popular target for small telescopes. It’s undergoing a period of extensive star formation that makes it many times brighter than our own Milky Way galaxy.
Image Credit: NASA