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Using the Webb Space Telescope, astronomers have obtained the first wide full infrared view of the supernova remnant Cassiopeia A, the remains of a supernova that occurred about 11,000 years ago. That image is to the right, reduced to post here.
The most noticeable colors in Webbโs newest image are clumps represented in bright orange and light pink that make up the inner shell of the supernova remnant. Webbโs razor-sharp view can detect the tiniest knots of gas, comprised of sulfur, oxygen, argon, and neon from the star itself. Embedded in this gas is a mixture of dust and molecules, which will eventually become components of new stars and planetary systems. Some filaments of debris are too tiny to be resolved by even Webb, meaning they are comparable to or less than 10 billion miles across (around 100 astronomical units). In comparison, the entirety of Cas A spans 10 light-years across, or 60 trillion miles.
…When comparing Webbโs new near-infrared view of Cas A with the mid-infrared view, its inner cavity and outermost shell are curiously devoid of color. The outskirts of the main inner shell, which appeared as a deep orange and red in the MIRI image, now look like smoke from a campfire. This marks where the supernova blast wave is ramming into surrounding circumstellar material. The dust in the circumstellar material is too cool to be detected directly at near-infrared wavelengths, but lights up in the mid-infrared.
The four rectangles mark specific features of particular interest, with #4, dubbed by the scientists Baby Cas, the most intriguing.
This is a light echo, where light from the starโs long-ago explosion has reached and is warming distant dust, which is glowing as it cools down. The intricacy of the dust pattern, and Baby Cas Aโs apparent proximity to Cas A itself, are particularly intriguing to researchers. In actuality, Baby Cas A is located about 170 light-years behind the supernova remnant.
By comparing this infrared view with Hubble’s optical and Chandra’s X-ray views, astronomers will be able to better decipher Cas A’s make-up and geometry.
