A global team of scientists has conducted fresh investigations into a unique supernova, identifying it as the most metal-poor stellar explosion ever seen.
This exceptional supernova, designated 2023ufx, resulted from the collapse of a red supergiant star and exploded at the edge of a nearby dwarf galaxy. The study’s findings revealed that both the supernova and the galaxy it was found in exhibit low metallicity, indicating a scarcity of elements heavier than hydrogen or helium.
Understanding the metals produced in supernovae is crucial as they clarify properties related to the evolution and demise of stars. By studying their formation, astronomers can glean insights into the state of the universe at its inception, particularly because there were virtually no metals present at that time, explained Michael Tucker, the study’s lead author and a fellow at the Center for Cosmology and AstroParticle Physics at The Ohio State University.
“For those interested in predicting the formation of the Milky Way, it’s essential to comprehend how the initial exploding stars influenced subsequent generations,” Tucker added. “This knowledge provides scientists with a valuable example of the impact those first stars had on their environment.”
Dwarf galaxies serve as helpful local analogs for scientists looking to understand the conditions expected in the early universe. According to Tucker, while the initial galaxies were low in metals, larger and brighter galaxies near the Milky Way had ample time for stars to explode and enrich their metallic content.
The metal content of a supernova also affects various characteristics, such as the number of nuclear reactions it may initiate and the duration of its brightness. This is partly why many low-mass stars are also at risk of collapsing into black holes.
The findings were recently published in The Astrophysical Journal.
Although the event spotted by Tucker’s team marks only the second supernova with low metallicity, its location in relation to the Milky Way is particularly noteworthy, according to Tucker.
Typically, astronomers predict that metal-poor supernovae would be faint and difficult to detect due to their distance from our galaxy. However, advancements in technology, especially with NASA’s James Webb Space Telescope, have significantly simplified the process of observing distant metal-poor galaxies.
The discovery of 2023ufx was somewhat serendipitous for the researchers. Their observations showed that this supernova exhibited several distinct characteristics compared to others in nearby galaxies.
Specifically, this supernova maintained a consistent brightness for roughly 20 days before fading, while metal-rich supernovae typically remain bright for around 100 days. Additionally, the study revealed that a significant amount of rapidly moving material was expelled during the explosion, indicating that it was likely spinning very fast at the time of its explosion.
This suggests that rapidly spinning, metal-poor stars were quite common in the universe’s early days, according to Tucker. His team theorizes that the supernova had relatively weak stellar winds—particle streams emitted from the star’s atmosphere—which could have contributed to the enormous energy it released.
All in all, their findings pave the way for astronomers to explore how metal-poor stars thrive in varying cosmic environments and may assist theorists in refining models of how supernovae functioned in the early universe.
“For anyone looking to predict how galaxies arise and evolve, it’s crucial to have a solid understanding of how the first exploding stars shaped their surroundings,” Tucker stated.
Future studies may focus on whether the supernova was previously larger, possibly as a supermassive star or if its material was removed by an as-yet-undiscovered binary partner.
In the meantime, researchers are awaiting more data to emerge.
“We are still in the early stages of the JWST era and learning about galaxies, so much remains to be understood,” said Tucker. “The hope is that this study serves as a reference point for future discoveries.”
This research was funded by the National Science Foundation, the European Research Council (ERC), the Australian Research Council Discovery Early Career Researcher Award (DECRA), and NASA. Christopher S. Kochanek from Ohio State also contributed as a co-author.
