The unusual green feature in the star remnant spotted last year called for extensive combined research of data from various telescopes.
We know that we are just a minuscule part of this planet. But to know that our planet is a minute part of an immeasurably humongous universe is quite captivating. Recently, astronomers have s the mystery of the "Green Monster" found in Cassiopeia A - a supernova remnant created 340 years ago as the result of a cosmic explosion. In an elaborate article, NASA shared the reason behind the unusual structure found in the debris of a star that collapsed thousands of years ago. While the James Webb Space Telescope picked up this "Green Monster" in April 2023, data from the Smithsonian Astrophysical Observatory's (SAO) Chandra X-ray Centre (CXC) has now revealed its components.
The analysis of the composite image of X-ray image from CXC, infrared data from Webb and optical data from the Hubble telescope revealed that the unusual structure was made up of hot gas from the supernova debris and contained elements like silicon and iron. The astronomers were able to identify the infrared radiation from the warmed-up stardust as detected by Webb. The Chandra image was color-coded based on the X-ray energies. So, the supernova structure being discussed was not originally green but was assigned the color due to the wavelength in which the filament was glowing. That being said, the Chandra image showed the presence of iron and magnesium in red, silicon in green and electrons spiraling around the magnetic field lines of the blast in blue.
On further examination, the researchers found that the "Green Monster" was the result of the blast wave from the explosion colliding with the materials around it. The shock waves from the explosion were as powerful as sonic booms from supersonic planes, creating the unusual heated-up structure. It only proves that the "Green Monster" materials were the ones surrounding the star before the explosion.
But the real question was, what lay behind it that could tell us something about the explosion and the star's composition? "We then digitally removed the Green Monster from the rest of the image to learn more about what is behind it. It's like we were handed a completed, 3D jigsaw puzzle and we were able to take parts out to see what's on the inside," said the Webb study's co-investigator Ilse De Looze from Ghent University, Belgium, as per Chandra X-Ray Observatory.
Unlike the heated-up debris found by Chandra, the astronomers found some unimpacted "pristine" debris behind the green structure in Webb's data. These pristine debris filaments were similar to the iron debris found in Chandra's data, along with some radioactive titanium in its weaker spots found by NASA's NuSTAR (Nuclear Spectroscopic Telescope Array).
A case of collaboration with Cas A.— NASA (@NASA) January 9, 2024
Combining the powers of @ChandraXray & @NASAWebb, scientists get a new look at supernova remnant Cassiopeia A. The findings reveal details of the nebula’s “Green Monster,” first spotted by Webb in 2023: https://t.co/kM95X2qecP #AAS243 pic.twitter.com/g87u9InTUQ
The extensive inspection of combined data revealed that the exploded star's core layers blended with extremely hot radioactive matter, creating the materials found in the 'pristine' debris. These materials, under gravity, caused the ultimate destruction of the star. What we saw as the 'Green Monster' in Cassiopeia A was just the impact of this massive collapse on the star's surrounding materials.
Tea Temim, one of the co-investigators of the Webb study, said that these conclusions about the supernova have "broad implications for the formation and evolution of stellar populations and the metal and dust enrichment of galaxies." The coherent utilization of various space technologies rendered the unraveling of the mystery behind the Green Monster by looking at it from diverse perspectives. The collective results not only highlight the composition of the Green Monster but also the source of such a consequential phenomenon in this measureless universe.