James Webb provides a second view of an exploded star

When massive stars run out of fuel and come to the ends of their lives, their final phase can be a massive explosion called a supernova. Although the bright flash of light from these events quickly fades, other effects are longer-lasting. As the shockwaves from these explosions travel out into space and interact with nearby dust and gas, they can sculpt beautiful objects called supernova remnants.

One such supernova remnant, Cassiopeia A, or Cas A, was recently imaged using the James Webb Space Telescope’s NIRCam instrument. Located 11,000 light-years away in the constellation of Cassiopeia, it is thought to be a star that exploded 340 years ago (as seen from Earth) and it is now one of the brightest radio objects in the sky. This view shows the shell of material thrown out by the explosion interacting with the gas that the massive star gave off in its last phases of life.

A new high-definition image from NASA’s James Webb Space Telescope’s NIRCam (Near-Infrared Camera) unveils intricate details of supernova remnant Cassiopeia A (Cas A), and shows the expanding shell of material slamming into the gas shed by the star before it exploded.The most noticeable colors in Webb’s newest image are clumps of bright orange and light pink that make up the inner shell of the supernova remnant. These tiny knots of gas, comprised of sulfur, oxygen, argon, and neon from the star itself, are only detectable by NIRCam’s exquisite resolution, and give researchers a hint at how the dying star shattered like glass when it exploded. — A new high-definition image from the James Webb Space Telescope’s NIRCam (Near-Infrared Camera) reveals intricate details of supernova remnant Cassiopeia A (Cas A), and shows the expanding shell of material slamming into the gas shed by the star before it exploded. NASA, ESA, CSA, STScI, Danny Milisavljevic (Purdue University), Ilse De Looze (UGent), Tea Temim (Princeton University)

“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,” said lead researcher Danny Milisavljevic of Purdue University 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.”

Webb has observed Cas A before, using its MIRI instrument. The previous observations taken by MIRI were in the mid-infrared wavelength, which looks more colorful and shows features like the warm dust surrounding the remnant, making up its outer shell, lit up in oranges and red.

This image provides a side-by-side comparison of supernova remnant Cassiopeia A (Cas A) as captured by NASA’s James Webb Space Telescope’s NIRCam (Near-Infrared Camera) and MIRI (Mid-Infrared Instrument). — From left, this image provides a side-by-side comparison of supernova remnant Cassiopeia A (Cas A) as captured by NASA’s James Webb Space Telescope’s NIRCam (Near-Infrared Camera) and MIRI (Mid-Infrared Instrument). NASA, ESA, CSA, STScI, Danny Milisavljevic (Purdue University), Ilse De Looze (UGent), Tea Temim (Princeton University)

This recent observation, on the other hand, was observed using NIRCam in the near-infrared wavelength. NIRCam has higher resolution than MIRI, so the image appears somewhat sharper, and it also picks out different details. The dust that glows so brightly in the mid-infrared is barely visible in the near-infrared, appearing as smoke-like wisps. Instead, the NIRCam image shows the inner shell of the remnant more clearly, which helps researchers to learn about how the star shattered when it exploded.

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