Using data from the Very Large Array Sky Survey, researchers have uncovered evidence for a theorized type of supernovae that had not previously been identified in the physical universe. Normal core-collapse supernovae occur when a massive star exhausts its fuel and can no longer withstand its own gravity. As a result, the star’s core collapses in on itself, triggering a supernova explosion that leaves behind a neutron star or black hole. 

Because most massive stars are born in close binary systems, these compact objects can remain in close orbits with their companion stars and potentially spiral inward until they merge. Theory predicts that these types of mergers would also trigger a similar stellar explosion – a merger-triggered core collapse supernova – but such events have not previously been observed. Using data from the Very Large Array Sky Survey, Dillon Dong and colleagues searched for transient radio sources and identified a very luminous radio source (VT J121001+4959647), which was not present in earlier radio surveys. 

Through follow-up radio and optical spectroscopy, Dong et al. show that the radio source is consistent with an expanding supernova remnant interacting with surrounding material, probably ejected from the star a few centuries before its explosion. What’s more, the authors associate this source with an unidentified x-ray transient that occurred in 2014 at a location consistent with VT J121001+4959647, suggesting that the explosion produced a relativistic jet. According to the authors, this combination of properties is most consistent with predictions for a merger-triggered supernova.