Scientists from the OzGrav–Swinburne University of the Netherlands have found evidence for the existence of large star explosions that leave behind a neutron star, a compact collapsed stellar core. The researchers detected an absence of black holes between 44 and 116 times the mass of the sun, which they called a "forbidden range". This could be explained if the largest stars, expected to leave behind these black holes, instead were destroyed in a rare type of explosion called a pair-instability supernova. These supernovas were predicted six decades ago but are rare and difficult to identify.