An animation sequence of the 17th century supernova in the constellation of Cassiopeia. Surrounding material plus continued emission of EM radiation both play a role in the remnant’s continued illumination. (NASA, ESA, and the Hubble Heritage STScI/AURA)-ESA/Hubble Collaboration. Acknowledgement: Robert A. Fesen (Dartmouth College, USA) and James Long (ESA/Hubble))

How Do The Most Massive Stars Die: Supernova, Hypernova, Or Direct Collapse?

We’re taught that the most massive stars in the Universe all die in supernovae. We were taught wrong.

Create a star that’s massive enough, and it won’t go out with a whimper like our Sun will, burning smoothly for billions upon billions of year before contracting down into a white dwarf. Instead, its core will collapse, leading to a runaway fusion reaction that blows the outer portions of the star apart in a supernova explosion, all while the interior collapses down to either a neutron star or a black hole. At least, that’s the conventional wisdom. But if your star is massive enough, you might not get a supernova at all. Another possibility is direct collapse, where the entire star just goes away, and forms a black hole. Still another is known as a hypernova, which is far more energetic and luminous than a supernova, and leaves no core remnant behind at all. How will the most massive stars of all end their lives? Here’s what the science has to say so far.

The nebula from supernova remnant W49B, still visible in X-rays, radio and infrared wavelengths. It takes a star at least 8–10 times as massive as the Sun to go supernova, and create the necessary heavy elements the Universe requires to have a planet like Earth. (X-ray: NASA/CXC/MIT/L.Lopez et al.; Infrared: Palomar; Radio: NSF/NRAO/VLA)

Every star, when it’s first born, fuses hydrogen into helium in its core. Sun-like stars, red dwarfs…