Figure 1: The Cassiopeia A supernova remnant as observed by NASA’s Chandra X-ray Observatory. Calculations by RIKEN based on Chandra data indicate that the progenitor star had a companion, which has yet to be observed. © NASA/CXC/SAO
The massive star that exploded to form the supernova known as Cassiopeia A most likely had a companion star that has yet to be spotted, a spectroscopic analysis by RIKEN astrophysicists suggests1. This will provide fresh impetus to efforts to locate the companion.
Supernovae are among the most violent events in the Universe. They occur when a massive star exhausts its supply of fuel and its core collapses under the huge gravitational pull of the star.