Astrophysics has just experienced a monumental discovery! A group of Yale scientists have discovered a new class of supernova called SN2021yfj. It was thanks to the Zwicky Transient Facility (ZTF) at Northwestern University that this extraordinary event was recorded and announced in September 2021. It complicates our current definitions of what stellar evolution is. Stationed a mind-boggling 2.2 billion light-years away from Earth, SN2021yfj has already generated plenty of excitement among scientists and laypeople.
The supernova is unusual for being so rich in silicon, sulfur and argon. This would indicate that the progenitor star lost its outer layers long before the explosion in the surrounding gas occurred. SN2021yfj’s progenitor was special. Instead of a normal stellar structure, it had only core of oxygen/silicon mix, so it was different from any stars known across the Milky Way. As if this historic event weren’t momentous enough, the implications are deep. It demonstrates that stars can lose up to a third of their mass before they die.
Discovering SN2021yfj
The finding of SN2021yfj became possible through the Zwicky Transient Facility, which focuses on discovering transient astronomical events. How the University of Oregon team came to critical realizations. They found that the progenitor star had a high mass loss, removing its outer hydrogen, helium and carbon layers long before the eventual SN explosion.
Steve Schulze, the lead researcher directly engaged in the analysis, noted something shocking. He continued on, “This is the first time we have seen a star that was literally shaved down to the bare bones. This unprecedented observation represents the first ever direct observational confirmation of theoretical predictions of the life cycle of massive stars and their eventual explosive demise.
The analysis of SN2021yfj’s spectrum was conducted using advanced instruments at the W.M. Keck Observatory in Hawai’i. The information provided by these observations was key in solidifying how unusual the supernova and progenitor really were.
Implications for Stellar Evolution
The strange characteristics of SN2021yfj suggest that our understanding of stellar evolution may be wrong. Adam Miller, another researcher involved in the work, echoed that enthusiasm in a terrific quote. He explained, “This event very literally appears like nothing anybody has seen before.” He further elaborated on the significance of the findings: “It shows us how stars are structured and proves that stars can lose a lot of material before they explode.”
SN 2021yfj was exploded by a rare and clean powerful process. Cannonade of huge shells during the star’s death throes met head on. This titanic collision created a radiant spectacle that astronomers quickly identified as a supernova. Stuck inside that most recent shell ejection, Schulze noticed, was a collision with an already-present shell. It’s this dramatic encounter that generated the remarkable light we saw as SN2021yfj.
Regardless, this finding opens fascinating new doors in understanding how the most massive stars can die. It further implies that all of this textbook material may not be illustrative of the full spectrum of stellar behavior. Miller commented on this revelation: “It’s not that our textbooks are incorrect, but they clearly do not fully capture everything produced in nature.”
Exploring Future Research
SN2021yfj’s unusual features highlight the necessity of investigating more cases like these. Scientists are understandably excited about having a better handle on these rare supernovae and what they may tell us about stellar evolution theories. Miller emphasized the importance of gathering more data: “I wouldn’t bet my life that [our theory] is correct, because we still only have one discovered example.”
More of these rare supernovae should be found,” he stated in conclusion. Only then can we know what’s formed their characters, how they’ve formed and shifted over time. It took the researchers weeks of frustration before they finally managed to see this supernova. Miller remembered the crushing feeling when they thought they had lost their window for observations. One lost science chance “We truly felt like we had completely lost our chance to get these observations,” he added.
Then serendipity intervened, as a result of an unfortunate mistake — a colleague at UC Berkeley by chance sent them the wrong spectrum that altered their course. “Without that spectrum we might never have figured out that this was a strange and unusual explosion,” said Miller.
Schulze added that although they witnessed an important explosion at first, they had no concept of what it was actually particle-wise. It was pretty clear that we were seeing something super interesting blow up, we just had no clue what it was. This deepens the impression that every astronomical event is a mystery waiting to be solved by follow-up research.