Astronomers now have some idea of how the first stars died
Scientists have long been interested in how the first stars were born, and in 2015 they even found a new galaxy that appeared to contain first-generation stars. But another major outstanding question in astronomy is how these first stars died. While we typically assume that these died in unimaginably powerful spherical explosions, called “supernovae,” these energetic events have been notoriously tricky to simulate — even with supercomputers at our disposal.
Now, a team of researchers from across the USA has published results that point to an entirely different picture of these first stars’ fiery deaths. Rather than the spherical explosions astronomers have long imagined, this new observational evidence suggests that the first stars ended their lives aspherically, spewing jets of material at random directions out into space.
Their result comes from observations of a very old, bright, and metal-poor star called HE 1327−2326. This star was born out of the remnants of the first generation of stars, and so studying it can help shed light on what the lives and deaths of these first stars were like. Surprisingly, they found much more zinc — an element that is only created in the cores of massive stars — than they expected. If the first generation of stars really did explode spherically, most of the material shot outward during these explosions should have fallen back in to the black holes left behind. And after running 10,000 computer simulations to try to figure out where this zinc came from, the team found that this was the case: not a single simulation of a spherical explosion was able to reproduce their observations.
Apsherical explosions would allow zinc to be flung far away, while other material could have fallen in to the stellar remnant. Although the researchers aren’t sure how common these aspherical supernovae were, their results will help inform future research and shed light on other questions surrounding these mysterious first stars.