Around 11,300 years back, an enormous star teetered on the precipice of annihilation. It pulsed with energy as it expelled its external layers, shedding the product into area. Ultimately it took off as a supernova, and its residue is among the most studied supernova residues (SNR). It’s called Cassiopeia A (Cas A) and brand-new observations with the Chandra X-ray telescope are exposing more information about its death.

Cas A’s progenitor star had in between about 15 to 20 solar masses, though some quotes vary as high as 30 solar masses. It was likely a red supergiant, though there’s dispute about its nature and the course it followed to blowing up as a supernova. Some astrophysicists believe it might have been a Wolf-Rayet star.

In any case, it ultimately took off as a core-collapse supernova. Once it developed an iron core, the star might no longer support itself and blew up. The light from Cas A’s death reached Earth around the 1660s.

There are no conclusive records of observers seeing the supernova surge in the sky, however astronomers have actually studied the Cas A SNR in fantastic information in modern-day times and throughout numerous wavelengths.

This is a composite incorrect colour picture of Cassiopeia A. It consists of information from the Hubble Space Telescope, the Spitzer Space Telescope, and the Chandra X-ray telescope. (Image credit: NASA/JPL-Caltech)New research study in The Astrophysical Journal discusses Chandra’s brand-new findings. It’s entitled “Inhomogeneous Stellar Mixing in the Final Hours before the Cassiopeia A Supernova.” The lead author is Toshiki Sato of Meiji University in Japan.

“It seems like each time we closely look at Chandra data of Cas A, we learn something new and exciting,” stated lead author Sato in a news release. “Now we’ve taken that invaluable X-ray data, combined it with powerful computer models, and found something extraordinary.”

Among the issues with studying supernovae is that their ultimate surges are what activate our observations. An in-depth understanding of the last minutes before a supernova takes off is hard to get.

The lead up to the SN surge of a huge star includes the nucleosynthesis of progressively heavy components deeper into its interior. The surface area layer is hydrogen, then helium is next, then carbon and even much heavier aspects under the external layers. Ultimately, the star develops iron. Iron is a barrier to this procedure, due to the fact that while lighter components launch energy when they fuse, iron needs more energy to go through more blend. The iron develops in the core, and as soon as the core reaches about 1.4 solar masses, there’s insufficient outside pressure to avoid collapse. Gravity wins, the core collapses, and the star blows up.

This high-definition image from NASA’s James Webb Space Telescope’s NIRCam(Near-Infrared Camera)reveals complex information of supernova residue Cassiopeia A(Cas A), and reveals the broadening shell of product slamming into the gas shed by the star before it took off. (Image credit: NASA, ESA, CSA, STScI, Danny Milisavljevic (Purdue University), Ilse De Looze (UGhent), Tea Temim(Princeton University))Chandra’s observations, integrated with modelling, are providing astrophysicists an appearance inside the star throughout its last minutes before collapse.

“Our research shows that just before the star in Cas A collapsed, part of an inner layer with large amounts of silicon traveled outwards and broke into a neighboring layer with lots of neon,” stated co-author Kai Matsunaga of Kyoto University in Japan. “This is a violent event where the barrier between these two layers disappears.”

The outcomes were two-fold. Silicon-rich product took a trip external, while neon-rich product took a trip inward. This developed inhomogeneous blending of the aspects, and little areas abundant in silicon were discovered near little areas abundant in neon.

Inhomogeneous essential circulation in Cas A observed by Chandra. The distinction in the blending ratio of blue and green colors plainly reveals the various structure in the O-rich ejecta. The red, green, and blue consist of emission within energy bands of 6.54– 6.92 keV (Fe Heα), 1.76– 1.94 keV(Si Heα), and 0.60– 0.85 keV(O lines), respectively. The ejecta highlighted in red and green are items of explosive nucleosynthesis, while the ejecta in blue and emerald green show excellent nucleosynthesis. The circles in the little panels are O-rich areas utilized for spectral analysis. The areas of low and high X-ray strength in the Si band are suggested by the magenta and cyan circles, respectively. (Image credit: Toshiki Sato et al., 2025; CC BY 4.0)This becomes part of what the scientists call a ‘shell merger’. They state it’s the last stage of outstanding activity. It’s an extreme burning where the oxygen burning shell swallows the external Carbon and Neon burning shell deep inside the star’s interior. This takes place just minutes before the star takes off as a supernova. “In the violent convective layer created by the shell merger, Ne, which is abundant in the stellar O-rich layer, is burned as it is pulled inward, and Si, which is synthesized inside, is transported outward,” the authors discuss in their research study.

This schematic reveals the interior of an enormous star in the procedure of a ‘shell merger.’It reveals both the down plumes of Neon-rich product and the upward plumes of silicon-rich product. (Image credit: Toshiki Sato et al., 2025; CC BY 4.0)The intermingled silicon-rich and neon-rich areas are proof of this procedure. The authors discuss that the silicon and neon did not blend with the other aspects either right away before or right away after the surge. Astrophysical designs have actually anticipated this, it’s never ever been observed before. “Our results provide the first observational evidence that the final stellar burning process rapidly alters the internal structure, leaving a pre-supernova asymmetry,” the scientists discuss in their paper.

For years, astrophysicists believed that SN surges were in proportion. Early observations supported the concept, and the fundamental concept behind core-collapse supernovae likewise supported balance. This research study alters the essential understanding of supernova surges as unbalanced. “The coexistence of compact ejecta regions in both the “O-/ Ne-rich” and “O-/ Si-rich” regimes implies that the merger did not fully homogenize the O-rich layer prior to collapse, leaving behind multiscale compositional inhomogeneities and asymmetric velocity fields,” the scientists compose in their conclusion.

This asymmetry can likewise discuss how the neutron stars left get their velocity kick and cause high-velocity neutron stars.

These last minutes in a supernova’s life might likewise set off the surge itself, according to the authors. The turbulence produced by the inner chaos might have helped the star’s surge.

“Perhaps the most important effect of this change in the star’s structure is that it may have helped trigger the explosion itself,” stated co-author Hiroyuki Uchida likewise of Kyoto University. “Such final internal activity of a star may change its fate — whether it will shine as a supernova or not.”

“For a long time in the history of astronomy, it has been a dream to study the internal structure of stars,” the scientists compose in their paper’s conclusion. This research study has actually provided astrophysicists a vital peek into a progenitor star’s last minutes before surge. “This moment not only has a significant impact on the fate of a star, but also creates a more asymmetric supernova explosion,” they conclude.

The initial variation of this post was released on Universe Today