| A stellar-mass black hole forms when a heavy star collapses under its own weight in a supernova explosion. |
| Only a dozen such hypergiants are known, and scientists suspect that Rho Cassiopeiae will soon destroy itself in a supernova explosion. |
| When massive stars die, most of their energy is released as neutrinos in violent supernova explosions. |
| The astronomers realised that a normal red supergiant alone could not have given rise to such a weird supernova. |
| The supernova observations call out for some gravitationally repulsive substance to drive the cosmic acceleration. |
| For nebulas there are emission nebula, reflection nebulas, planetary nebulas, dark nebulas and supernova remnants. |
