\t\t\t\t\t\t11\/12\/2023<\/span> Like a shiny, round ornament ready to be placed in the perfect spot on the holiday tree, supernova remnant Cassiopeia A (Cas A) gleams in a new image from the NASA\/ESA\/CSA James Webb Space Telescope. However, this scene is no proverbial silent night\u00a0\u2013 all is not calm.<\/p>\n<\/div>\n Webb\u2019s NIRCam\u00a0(Near-Infrared Camera) view of Cas A displays a very violent explosion at a resolution previously unreachable at these wavelengths. This high-resolution look unveils intricate details of the expanding shell of material slamming into the gas shed by the star before it exploded.<\/p>\n Cas A is one of the best-studied supernova remnants in all the cosmos. Over the years, ground-based and space-based observatories, including the NASA\/ESA\u00a0Hubble Space Telescope, have collectively assembled a multiwavelength picture of the object\u2019s tattered remains.<\/p>\n However, astronomers have now entered a new era in the study of Cas A. In\u00a0April 2023, Webb\u2019s MIRI (Mid-Infrared Instrument) started this story, revealing new and unexpected features within the inner shell of the supernova remnant. But many of those features are invisible in the new NIRCam image, and astronomers are investigating why that is.<\/p>\n Infrared light is invisible to our eyes, so image processors and scientists represent these wavelengths of light with visible colours. In this newest image of Cas A, colours were assigned to NIRCam\u2019s different filters, and each of those colours hints at different activity occurring within the object.<\/p>\n At first glance, the NIRCam image may appear less colourful than the MIRI image. However, this does not mean there is less information: it simply comes down to the wavelengths in which the material in the object is emitting its light.<\/p>\n<\/p><\/div>\n <\/figcaption><\/figure>\n The most noticeable colours in Webb\u2019s newest image are clumps of bright orange and light pink that make up the inner shell of the supernova remnant. Webb\u2019s razor-sharp view can detect the tiniest knots of gas, composed of sulphur, oxygen, argon, and neon from the star itself. Embedded in this gas is a mixture of dust and molecules, which will eventually be incorporated into new stars and planetary systems. Some filaments of debris are too tiny to be resolved, even by Webb, meaning that they are comparable to or less than 16 billion km across (around 100 astronomical units). In comparison, the entirety of Cas A spans 10 light-years, or roughly 96 trillion km.<\/p>\n When comparing Webb\u2019s new near-infrared view of Cas A with the mid-infrared view, its inner cavity and outermost shell are curiously devoid of colour. 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 the 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.<\/p>\n Researchers have concluded that the white colour is light from synchrotron radiation, which is emitted across the electromagnetic spectrum, including the near-infrared. It\u2019s generated by charged particles travelling at extremely high speeds and spiralling around magnetic field lines. Synchrotron radiation is also visible in the bubble-like shells in the lower half of the inner cavity.<\/p>\n 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 light, appropriately nicknamed the Green Monster by the research team. This feature was described as \u2018challenging to understand\u2019 by researchers at the time of their first look.<\/p>\n While the \u2018green\u2019 of the Green Monster is not visible in NIRCam, what\u2019s 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\u00a0\u2013 this represents ionised gas. Researchers believe this is due to the supernova debris pushing through and sculpting gas left behind by the star before it exploded.<\/p>\n Researchers were also absolutely stunned by one fascinating feature at the bottom right corner of NIRCam\u2019s field of view. They\u2019re calling that large, striated blob Baby Cas A\u00a0\u2013 because it appears like an offspring of the main supernova.<\/p>\n This is a light echo. Light from the star\u2019s long-ago explosion has reached, and is warming, distant dust, which glows as it cools down. The intricacy of the dust pattern, and Baby Cas A\u2019s 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.<\/p>\n There are also several other, smaller light echoes scattered throughout Webb\u2019s new portrait.<\/p>\n The Cas A supernova remnant is located 11 000 light-years away in the constellation Cassiopeia. It\u2019s estimated to have exploded about 340 years ago from our point of view.<\/p>\n<\/p><\/div>\n \nMore information<\/b> Webb is an international partnership between NASA, ESA and the Canadian Space Agency (CSA).<\/p>\n Release on esawebb.org<\/p>\n \nContact:<\/b>
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Webb\u00a0is the largest, most powerful telescope ever launched into space. Under an international collaboration agreement, ESA provided the telescope\u2019s launch service, using the Ariane 5 launch vehicle. Working with partners, ESA was responsible for the development and qualification of Ariane 5 adaptations for the Webb mission and for the procurement of the launch service by Arianespace. ESA also provided the workhorse spectrograph\u00a0NIRSpec\u00a0and 50% of the mid-infrared instrument\u00a0MIRI, which was designed and built by a consortium of nationally funded European Institutes (The MIRI European Consortium) in partnership with JPL and the University of Arizona.<\/p>\n
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