Astronomers have captured the first image of a star that exploded twice, revealing a unique pattern of debris layers. This discovery, located in the Large Magellanic Cloud, showcases two distinct shells rich in calcium, with a sulfur layer nestled between them. The pattern matches predictions of a double detonation, where one explosion begins in the star's helium layer, and the other ignites in its carbon-oxygen core. This finding challenges previous assumptions about Type Ia supernovae, which are powerful stellar explosions that briefly outshine an entire galaxy. The study, published in Nature Astronomy, highlights the importance of understanding the diverse trigger mechanisms of these explosions, as they serve as crucial distance markers in the cosmos. The remnants of the star, known as SNR 0509-67.5, are a near-perfect sphere expanding into low-density gas, with shock waves peeling back outer layers to expose deeper structures. The calcium shells, separated by a sulfur peak, provide a clear indication of a two-stage trigger, supporting computer models that simulate star explosions under fluid dynamics. This discovery not only advances our understanding of Type Ia supernovae but also emphasizes the need for better three-dimensional radiative transfer models to refine distance measurements. The study's findings offer valuable insights into the complex nature of stellar explosions and the universe's expansion.
