SN2021yfj offers direct view into inner layers of a dying star

An international team of astronomers led by Northwestern University has identified a supernova never seen before, SN2021yfj, that exploded after losing nearly all of its outer layers and revealed a core enriched with silicon, sulfur and argon. The finding provides a rare, direct glimpse into the inner structure of a massive star just before its death, offering fresh evidence for the onion-like layering theorized to exist in these stellar giants and suggesting more exotic pathways for how such stars can end their lives.

The discovery began with data from the Zwicky Transient Facility, a wide-field survey that scans the night sky for fleeting cosmic events. Researchers spotted SN2021yfj in September 2021 in a star-forming region about 2.2 billion light-years from Earth. Because the event appeared unusually luminous, the team sought a detailed spectral analysis to identify the elements produced in the explosion. After initial attempts were hampered by weather and scheduling constraints, a colleague in California obtained a spectrum with instruments at the Keck Observatory in Hawaii, enabling the team to confirm that the explosion was unlike typical stripped supernovae.