In some supernova cases, astronomers find no trace of the former star’s outermost layer of hydrogen. What happened to the hydrogen? Suspicions that companion stars are responsible — siphoning away their partners’ outer shell before a catastrophic explosion — are supported by Hubble’s identification of a surviving companion star on the scene of the Type Ib/c supernova (SN) 2013ge. An artist’s illustration shows SN 2013ge, with its...
