What evidence shows that Cassiopeia A resulted from the collapse of a massive star?
This nebula is the product of a supernova explosion; in this section, the blast wave has encountered an area of dense interstellar gas, creating turbulence in the wave and causing it to glow. The picture is a composite of three images taken by the Hubble Space Telescope.
Evidence that Cassiopeia A resulted from the collapse of a massive star is primarily provided by the presence of a neutron star at the center of the remnant.1
In astronomy, the formation of a neutron star is a hallmark of a core-collapse supernova, which occurs when a massive star exhausts its nuclear fuel and its core collapses under gravity. Furthermore, Cassiopeia A is identified as a supernova remnant, a structure formed when a star ejects the majority of its mass in a violent explosion. The remnant appears as an expanding ring of material, and its expansion rate has been used to estimate the timing of the original explosion. While the event itself was likely obscured by interstellar dust clouds, the remnant remains a powerful source of radio emission, providing scientists with the data necessary to confirm its origin as a massive stellar collapse.12