The second image is from about two days later and the third from about six days after that. In these two images, the gaseous material ejected from the star is seen expanding outward. In the second image, the explosion is only a fifth as hot as in the first one. In the third image, it is only a tenth as hot as the first.
The remnant of the exploded star most likely became an incredibly dense object called a neutron star, Chen said.
A phenomenon called strong gravitational lensing accounts for how Hubble was able to obtain three images at different points in time after the explosion. The tremendous gravitational power exerted by a galaxy cluster located in front of the exploding star from the perspective of Earth served as a lens - bending and magnifying the light emanating from the supernova.
"The gravity in the galaxy cluster not only bends the light from behind it, but also delays the light travel time because the stronger the gravity, the slower a clock moves," Chen said. "In other words, emission of light from a single source behind the lens can go through multiple paths toward us, and we then see multiple images of the source."
Kelly called the ability to see the rapidly cooling supernova in a single set of images thanks to gravitational lensing "just absolutely amazing."
"It's kind of like seeing a film reel in color of the supernova evolving, and it's a much more detailed picture of any known supernova that existed when the universe was a small fraction of its current age," Kelly said.
"The only other examples where we have caught a supernova very early are very nearby explosions," Kelly added. "When astronomers see more distant objects, they are looking back in time."
