NASA’s James Webb Space Telescope (JWST) has snapped a picture of Cassiopeia A (CasA), a dramatic structure left behind by the death throes of a star that exploded from Earth’s perspective about 340 years ago.
Using its powerful near-infrared camera (NIRCam), JWST peered through Cas A’s cosmic dust to reveal never-before-seen structures of the expanding shell of material hitting the gas shed by the star.
Studying these structures could help us understand how stardust spreads through the universe and how it helps, ultimately, create life.
“With NIRCam’s resolution, we can now see how the dying star absolutely shattered when it exploded, leaving filaments akin to tiny shards of glass behind,” research lead Danny Milisavljevic of Purdue University said in a statement.
“It’s really unbelievable after all these years studying Cas A to now resolve those details, which are providing us with transformational insight into how this star exploded.”
Studying a supernova remnant is like looking at a stellar “autopsy” Milisavljevic said in a previous statement.
Scientists study these images closely to reconstruct what a star might have looked like and what happened when it bursts.
JWST uncovered delicate structures in Cas A like “shards of glass” Milisavljevic said, which could be remnants of the star itself glowing in pink and gold as the dead star’s sulfur, oxygen, neon, and argon interact with nearby dust.
JWST also uncovered cosmic “bullet holes” behind a green cloud of cosmic gas that previously hid scientist’s view, NASA said in an accompanying video. These are thought to be made by ionized gas punching through other gas left behind by the star.
A new structure, nicknamed “Baby Cas A” by the researcher, also appeared in JWST’s field of view.
Scientists are excited about this structure, because it is thought to have caught an “echo” of the explosion, seen as light from the supernova that is interacting with cosmic dust. Though it looks a lot smaller than Cas A, “Baby Cas A” is about 170 light-years behind the supernova remnant.
Cas A has been particularly helpful in studying stellar forensics. It is relatively close to us, about 11,000 light-years away in the constellation Cassiopeia.
It’s also the youngest known remnant of a massive star in our galaxy, so what scientists are seeing is the very beginning of the event.
Understanding the last moments of nearby stars is important because they hold some of the building blocks of life. They spread calcium and iron through the cosmos, without which we wouldn’t have bones or blood.
“By understanding the process of exploding stars, we’re reading our own origin story,” said Milisavljevic.