New Webb image shows stunning details of a dead star's remnants

The picture could help inform our current knowledge of where the building blocks of planets and ourselves first emerged.
Loukia Papadopoulos
Webb image of Cas A.jpg
Webb image of Cas A.


A new mid-infrared image from NASA’s James Webb Space Telescope is providing great details of the explosion of a star, and the remains it leaves behind. It shows the supernova remnant Cassiopeia A (Cas A) that was created by a stellar explosion 340 years ago.

This is according to a press statement published by NASA on Friday.

“Cas A represents our best opportunity to look at the debris field of an exploded star and run a kind of stellar autopsy to understand what type of star was there beforehand and how that star exploded,” said Danny Milisavljevic of Purdue University in West Lafayette, Indiana, principal investigator of the Webb program that captured these observations.

“Compared to previous infrared images, we see incredible detail that we haven't been able to access before,” added Tea Temim of Princeton University in Princeton, New Jersey, a co-investigator on the program.

Cassiopeia A has been widely studied by a number of observatories, including NASA’s Chandra X-ray Observatory, whose details can be combined to provide scientists with a more comprehensive understanding of the remnant.

In the new image, infrared light is translated into visible-light wavelengths resulting in substantial information the team of astronomers is just starting to explore. The image shows orange and red hues that are due to emissions from warm dust and delineate where ejected materials from the exploded star are ramming into surrounding circumstellar gas and dust.

“We’re still trying to disentangle all these sources of emission,” said Ilse De Looze of Ghent University in Belgium, another co-investigator on the program.

The Green Monster

Meanwhile, a vibrant loop represented in green lies across the right side of the central cavity. 

“We’ve nicknamed it the Green Monster in honor of Fenway Park in Boston. If you look closely, you’ll notice that it’s pockmarked with what look like mini-bubbles,” said Milisavljevic. “The shape and complexity are unexpected and challenging to understand.”

By studying the dead stars, astronomers hope to gain a better understanding of its dust content, which can help inform our current knowledge of where the building blocks of planets and ourselves first emerged

“In Cas A, we can spatially resolve regions that have different gas compositions and look at what types of dust were formed in those regions,” explained Temim.

“By understanding the process of exploding stars, we’re reading our own origin story,” said in the statement Milisavljevic. “I’m going to spend the rest of my career trying to understand what’s in this data set.”

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