New results from NASA's Chandra X-ray Observatory reveal that Cassiopeia A's progenitor star violently reshaped its interior just hours before it exploded.

This previously hidden stellar upheaval helps explain the asymmetry of the remnant and may even have triggered the supernova itself.

Cassiopeia A, one of the most studied remnants in the night sky, began as a massive star that lived for more than a million years.

As with other massive stars, its interior formed onion-like layers of hydrogen, helium, carbon, and heavier elements. When iron accumulated at the core, it collapsed under its own weight, initiating the explosion about three centuries ago.

Chandra's X-ray data, combined with advanced simulations, revealed that part of the silicon-rich inner layer broke outward into a neon-rich layer in the star's final hours.

This disruption forced silicon to move outward and neon to move inward, leaving clear evidence in Cas A's debris field: regions with abundant silicon but little neon adjacent to areas with the opposite composition.

Source:Spacedaily