💥 Only antimatter explains this absolute supernova - nothing remains - not even a black hole

A supernova so extreme that the star's death is total, leaving no black hole or neutron star behind: that is what astronomers think they have observed with the clearest example of such an event. Dubbed SN 2023vbw, this unusual explosion was detected at the edge of a small dwarf galaxy, about 1.3 billion light-years away.

In a pair-instability supernova, the core of an extremely massive star becomes so hot that it generates matter-antimatter pairs. This process reduces the pressure supporting the star against gravity, triggering a thermonuclear explosion so violent that the entire star is consumed. No neutron star or stellar black hole remains. Theory predicts this fate for stars of 140 to 260 solar masses with low metallicity. SN 2023vbw matches these criteria.


The event was first detected by the Zwicky Transient Facility in October 2023. Initially classified as a classic type II supernova, its behavior soon proved atypical. Its light curve showed a steady increase to a peak around 190 days, much longer than normal. Then it declined rapidly, before stabilizing into a slow decay. The total energy released was more than ten times that of an ordinary supernova.

During its rise in brightness, the explosion maintained an almost constant temperature while its outer layers continued to expand. This requires a continuous internal heating source, unlike classical supernovas. As it faded, emission lines appeared, and the hydrogen lines showed multiple components, indicating that the ejecta were interacting with a disk of material that the star had lost before its death.

Models indicate that the progenitor star was a blue supergiant, with an ejecta mass between 170 and 350 solar masses. The explosion's kinetic energy far exceeds what a core-collapse supernova can produce. The low metallicity of the host galaxy supports the pair-instability hypothesis. Moreover, this blue supergiant could have resulted from the merger of two massive stars in a binary system.

This merger scenario would naturally explain the disk-shaped envelope around the star. However, uncertainties remain: it is not yet known whether very massive stars end their lives as red or blue supergiants, nor at what point such a merger might occur. Despite these questions, SN 2023vbw remains a prime candidate for a pair-instability supernova.

Thanks to its relative proximity and brightness, SN 2023vbw offers astronomers the opportunity to study it in multiple wavelengths to understand the star's mass-loss history and the chemical elements produced during the explosion. Future missions, such as the Vera Rubin Observatory and the Nancy Grace Roman Space Telescope, are expected to detect dozens of similar events, revealing the death and evolution of the most massive stars in the Universe.

What is a pair-instability supernova?

In a pair-instability supernova, the core of a very massive star reaches extreme temperatures, on the order of a billion degrees. These temperatures are so high that gamma-ray photons produced in the core can transform into electron-positron pairs. This process reduces the radiation pressure that supports the star against gravity, causing a sudden collapse. The collapse triggers an explosive thermonuclear reaction that consumes the entire star.

This explosion is so violent that no compact remnant, such as a neutron star or black hole, remains. The supernova disperses all its material into space, enriching the interstellar medium with heavy elements. Models predict that only initially very massive stars (between 140 and 260 solar masses) with low metallicity can undergo this fate. Low metallicity is essential because it reduces mass loss from stellar wind, allowing the star to retain its high mass.

Pair-instability supernovas are extremely rare because they require very specific conditions. They are thought to have been more common in the early Universe, when stars were more massive and less metallic. Studying them helps astronomers understand the formation of the first heavy elements and the evolution of primordial galaxies.