2023-12-11 13:55:29
MADRID 11 (EUROPA PRESS)
The James Webb Space Telescope has taken an image of the supernova remnant Cassiopeia A (CAS A) to a resolution previously unattainable at infrared wavelengths of light.
This high-resolution look reveals intricate details of the expanding shell of material crashing into gas projected by the star before it exploded.
CAS A is one of the best-studied supernova remnants in the entire cosmos. It’s found 11,000 light years away in the constellation Cassiopeia. It is estimated that it exploded about 340 years ago from our point of view.
Over the years, ground-based and space-based observatories, including the NASA/ESA Hubble Space Telescope, have collectively assembled a multi-wavelength image of the object’s remains.
However, astronomers have now entered a new era in the study of CAS A. In April 2023, Webb’s MIRI intermediate-infrared instrument began 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.
Infrared light is invisible to our eyes, so image processors and scientists represent these wavelengths of light with visible colors. In this newer CAS A image, the colors were assigned to the different Nircam filters, and each of those colors suggests a different activity within the object.
At first glance, the Nircam image may appear less colorful than the Miri image. However, this does not mean that there is less information: it simply boils down to the wavelengths at which the material in the object is emitting its light, NASA reports.
The most notable colors in Webb’s newest image are clusters of bright orange and light pink that make up the inner layer of the supernova remnant. Webb’s keen vision can detect the smallest knots of gas, composed of sulfur, 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 in the debris are too small to be resolved, even by Webb, meaning they are comparable to or smaller than 16 billion km (about 100 astronomical units). By comparison, the entirety of CAS A spans 10 light years, or approximately 96 trillion km.
Comparing Webb’s 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 explosion wave is embarking on the surrounding circumstellar material. Dust in the circumstellar material is too cool to be detected directly at near-infrared wavelengths, but it illuminates in the mid-infrared.
Researchers have concluded that the white color is light from synchrotron radiation, which is emitted across the electromagnetic spectrum, including the near-infrared. It is generated by charged particles traveling at extremely high speeds and spiraling around magnetic field lines.. Synchrotron radiation is also visible in the bubble shells in the lower half of the internal cavity.
Also not seen in the near-infrared view is the loop of green light in CAS A’s central cavity that glowed in the mid-infrared light, appropriately dubbed the green monster by the research team. The researchers described this feature as “hard to understand” at the moment of your first look.
While the “green” of the green monster is not visible in Nircam, what remains in the near-infrared in that region may provide insight into the mysterious feature. The circular holes visible in the Miri image are slightly outlined in the white and purple emission in the Nircam image; this represents the ionized gas. Researchers believe this is because supernova debris pushes and sculpts gas left behind by the star before it exploded.
The researchers were also absolutely stunned by a fascinating feature in the lower right corner of Nircam’s field of view. They’re calling that big, striated baby baby Cas A, because it looks like a descendant of the main supernova.
This is a light echo. Light from the star’s explosion has reached, and is heating the distant dust, which glows as it cools. The complexity of the dust pattern, and the apparent proximity of Baby Cas A to CAS A itself, are particularly intriguing to researchers. In reality, Baby Cas A is located about 170 light years behind the supernova remnant.
There are also several other smaller light echoes scattered throughout Webb’s new portrait.
#Webb #amazes #image #supernova #Cassiopeia