This is the remnant of Kepler’s supernova, an explosion discovered by Johannes Kepler in 1604. The red, green and blue colors show low, intermediate and high energy X-rays observed with the Chandra X-ray Observatory. The star field is from the Digitized Sky Survey.
A recent study using Chandra has identified the trigger for this explosion. It was known that the explosion was a Type Ia supernova, a thermonuclear explosion of a white dwarf star, but there is an ongoing controversy about Type Ia supernovae. Are they caused by a white dwarf pulling so much material from a companion star that it becomes unstable and explodes, or do they result from the merger of two white dwarfs?
The new Chandra analysis shows that the Kepler supernova was triggered by an interaction between a white dwarf and a red giant star. The crucial evidence from the observations was a disk-shaped structure near the center of the remnant which seems to be caused by the collision between supernova debris and disk-shaped material that the giant star expelled before the explosion. It is also possible that the structure is just debris from the explosion.
Image Credit: NASA