Scientists discover that some of the universe's biggest explosions may have never happened at all

Scientists have discovered that some of the universe's most powerful explosions, hypernovas, may not occur as previously thought. Hypernovas were initially proposed to explain unusual stars in the Milky Way's halo and a neighboring dwarf galaxy. These stars were believed to form from the debris of an explosion ten times more powerful than average supernovas.

However, new research suggests that ordinary supernovas could account for these stars when considering the uneven or non-spherical way they eject matter. Lead researcher Anmol Aggarwal of University College London explained that mathematical models accounting for this phenomenon found that stars with an unusual mix of ingredients were most likely formed from ordinary supernovas.

The team developed mathematical models that took into account this uneven distribution of material and determined that stars with a very unusual mix of elements were most likely formed from ordinary supernovas. The evidence for hypernovas is now gone, as all the evidence previously supporting their existence has been eliminated.

Hypernovas and supernovas are similar explosions that occur when massive stars run out of fuel for nuclear fusion, sending shockwaves through their outer layers and ejecting elements into their surroundings. These elements become the building blocks of the next generation of stars. The researchers studied four stars suspected to have been formed from hypernova explosions and found that three of them were more likely to have been created after supernovas instead.

The team also examined a red giant star in the Milky Way's halo with an unusual chemical composition, including an overabundance of heavy elements. This star, which spins rapidly and exists at the outskirts of the Milky Way, was likely the result of a combination of a neutron star merger and an ordinary supernova rather than a hypernova.