Supernovae are some of the most energetic events in the Universe, sending massive shock waves out into the interstellar medium. And there’s every reason to think those shock waves run into things before they’ve had much of a chance to dissipate. Many stars have companions, either planets or other stars that orbit in reasonable proximity. In fact, there’s an entire subtype of supernova that appears to require a nearby companion.
So what happens to these objects when the shock wave hits? With our improved ability to rapidly identify supernovae, we may be on the cusp of finding out. Several times recently, researchers have spotted an extra blue glow to the burst of light from a supernova. And, in the most detailed observations yet, they make the case this glow comes from the supernova debris slamming into a companion star.
A supernova explosion that envelopes a nearby star is an inevitability. Eta Carinae, for example, is a system with two stars that are at least 30 times the Sun’s mass, meaning they’ll both eventually explode as a type-II supernova. Whichever goes first will undoubtedly send debris into the second. But there’s a different class of supernova, type-Ia, which requires the presence of a nearby star.