Exploding Star Stuns Scientists As Inner Layers Are Seen For The First Time

Scientists have for the first time peered inside a dying star as it exploded in a supernova, gaining not just unprecedented views of its layers, but more so, insight into the process of stellar evolution. Detailed in the Nature journal, the discovery offers direct evidence of the innermost layers of massive stars.

This particular event, dubbed supernova 2021yfj and located within the Milky Way, was unique because the exploding star's innermost layers were distinctively visible. Normally, the chaotic nature of a supernova explosion jumbles a star's layers, making it impossible for researchers to observe its internal composition. However, this particular star had already shed its outer layers of hydrogen and helium, and its dense, inner layers of silicon and sulfur were thus exposed during the explosion.

Massive stars, which can be 10 to 100 times heavier than our Sun, are onion-like. They are composed of distinct layers, with lighter elements such as hydrogen and helium on the outside and successively heavier elements closer to the core, culminating in an iron core. This layered structure is a result of nuclear fusion, whereby the star's extreme pressure and heat cause lighter elements to fuse into heavier ones, providing the energy that powers the star.

The observation of supernova 2021yfj provides a clear confirmation of this model. The fact that the silicon and sulfur layers were exposed before the explosion suggests the star lost a significant amount of its mass prior to its demise. Scientists are not yet certain what caused the star to shed so much material, speculating that it could have been violently ejected in the final stages of its life or pulled away by a companion star.