Evolution Scenario for a Stripped Envelope Supernova Illustration

This infographic shows the evolution astronomers propose for supernova (SN) 2013ge. Panels 1-3 show what has already occurred, and panels 4-6 show what may take place in the future. 1) A binary pair of massive stars orbit one another. 2) One star ages into its red giant stage, getting a puffy outer envelope of hydrogen that its companion star siphons off with gravity. Astronomers propose this is why Hubble found no trace of hydrogen in the supernova debris. 3) The stripped-envelope star goes supernova (SN 2013ge), jostling but not destroying its companion star. After the supernova, the dense core of the former massive star remains either as neutron star or black hole. 4) Eventually the companion star also ages into a red giant, maintaining its outer envelope, some of which came from its companion. 5) The companion star also undergoes a supernova. 6) If the stars were close enough to each other not to be flung from their orbits by the supernova blast wave, the remnant cores will continue to orbit one another and eventually merge, creating gravitational waves in the process.