Overview

• Northwestern-led researchers report in Nature that supernova SN 2021yfj occurred in our galaxy and offered an unprecedented view into a dying star’s interior.
• The star had already lost its outer hydrogen and helium, and the explosion also stripped dense inner silicon and sulfur layers, exposing deeper material.
• The result provides direct empirical support for the long-standing model of massive stars arranged in concentric elemental layers, external experts said.
• The mechanism behind the extreme mass loss remains unknown, with possibilities including violent late-stage ejections or removal by a binary companion.
• Key data came from the Zwicky Transient Facility and Keck Observatory, and future surveys such as the Rubin Observatory may reveal how rare such events are, with one outlet reporting the team’s tentative new subtype and extreme rarity.