End of life for a star as it goes supernova. This is an amazing image with debris expanding outward. Rather like imagining a nuclear bomb exploding in space and then multiply that by many billions. This certainly captures the power of nature’s cycles to refresh itself to eventually become a new Solar System.
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.
Researchers say the white color is light from synchrotron radiation, which is emitted across the electromagnetic spectrum, including the near-infrared. It’s generated by charged particles traveling at extremely high speeds spiraling around magnetic field lines. Synchrotron radiation is also visible in the bubble-like shells in the lower half of the inner cavity.
Also not seen in the near-infrared view is the loop of green light in the central cavity of Cas A that glowed in mid-infrared, nicknamed the Green Monster by the research team. This feature was described as “challenging to understand” by researchers at the time of their first look.
While the ‘green’ of the Green Monster is not visible in NIRCam, what’s left over in the near-infrared in that region can provide insight into the mysterious feature. The circular holes visible in the MIRI image are faintly outlined in white and purple emission in the NIRCam image – this represents ionized gas. Researchers believe this is due to the supernova debris pushing through and sculpting gas left behind by the star before it exploded.