Overview

• The Nature study reports unprecedented emission from ionized silicon, sulfur and argon, revealing inner shells that were exposed before the blast.
• Researchers designate the event “Type1en,” indicating a hydrogen‑poor supernova interacting with silicon‑ and sulfur‑rich circumstellar material.
• ZTF discovered the transient in September 2021 and Keck secured a spectrum about 24 hours later, with monitoring over 120 days at a distance of roughly 2.2 billion light‑years.
• Typical light‑element signatures were absent or weak, yet a faint helium signal is present, posing a key unresolved puzzle for stellar‑evolution models.
• Analyses imply an ejection of about three solar masses in a single episode, with ideas such as pulsational pair‑instability considered but not confirmed, highlighting the need for rapid follow‑up to find similar rare events.