Extremely stripped supernova reveals a silicon and sulfur formation site

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By Steve Schulze et al, Nature. 

Abstract: Stars are initially powered by the fusion of hydrogen to helium. These ashes serve as fuel in a series of stages1,2,3, transforming massive stars into a structure of shells. These are composed of natal hydrogen on the outside and consecutively heavier compositions inside, predicted to be dominated by He, C/O, O/Ne/Mg and O/Si/S (refs. 4,5). Silicon and sulfur are fused into iron, leading to the collapse of the core and either a supernova explosion or the formation of a black hole6,7,8,9. ...Here we report the discovery of the supernova (SN) 2021yfj resulting from a star stripped to its O/Si/S-rich layer. We directly observe a thick, massive Si/S-rich shell, expelled by the progenitor shortly before the supernova explosion.... [From ScienceAdvisor: Researchers spotted the consequential supernova, called SN 2021yfj, from California’s Zwicky Transient Facility, .... They found that the exploded star was about 60 times the mass of our Sun, 2.2 billion light-years away, and exhibited clear layers of heavier elements like argon and sulfur usually obscured behind its lighter outsides. The work “confirms this onionskin structure of massive stars that we all expected to see,” astrophysicist Matt Nicholl tells The New York Times.] 

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