Free Astronomy Magazine September-October 2022

43 SEPTEMBER-OCTOBER 2022 ASTRO PUBLISHING Astronomers detect the signature of various elements in supernova ex- plosions. These elements are layered like an onion pre-supernova. Hydro- gen is found in the outermost layer of a star, and if no hydrogen is de- tected in the aftermath of the su- pernova, that means it was stripped away before the explosion occurred. T his artist’s illustration shows supernova 2013ge, with its companion star at lower left. The companion star is impacted by the blast wave from the su- pernova, but not destroyed. Over time astronomers observed the ultraviolet (UV) light of the supernova fading, revealing a nearby second source of UV light that maintained brightness. The theory is that the two massive stars evolved together as a binary pair, and that the current survivor siphoned off its part- ner’s outer hydrogen gas shell before it exploded. Eventually, the companion star will also go supernova. [NASA, ESA, Leah Hustak (STScI)]