Ancient stars, nearly devoid of heavy elements, are like fossilized remnants of the first cosmic flashes. For a long time, the odd ratio of carbon, hydrogen, and helium in three such stars was thought to require a hypernova — an ultra-bright supernova with hundreds of times more energy than a regular one. But new research shows that a run-of-the-mill supernova is enough, if its ejecta doesn't spread uniformly, but in patches.
The explosion of a star resembles a spray can: even from a single nozzle, the paint settles unevenly, creating a whimsical pattern. Similarly, a supernova ejects elements in clumps, where one blob may contain dozens of times more carbon than its neighbor. The three "anomalous" stars simply formed within such carbon-rich patches.
Now all ancient stars with low heavy-element content will need to be reexamined: maybe their quirks are just a roll of the dice in cosmic sprinkling.
as written by the authors arXiv:2603.26873
Extremely low metallicity stars are intensely studied as they take observations the closest to the very first generations of stars in the universe. Widely assumed to be enriched by just one dying massive star, some of these very metal poor stars have abnormal chemical abundance ratios and have been taken to reflect a rare hypernova (with high explosion energy $$\gtrsim \ 10^{52}$$ erg.). Here we remodel the enrichment of three such stars and show that their abundances are better explained by enrichment from a normal (less energetic) supernova accounting for inhomogeneous distribution of the ejecta. This work establishes the importance of the inhomogeneity of supernovae, serves as a template for a required reassessment of all metal-poor/peculiar stars, and raises the need to quantify this inhomogeneity both in theory and in observations.
An ordinary supernova releases so much energy that it briefly outshines an entire galaxy.