Metal-poor supernova offers glimpse into cosmic past

Nov. 25 () –

Observations with the James Webb Space Telescope have revealed an unusual supernova and the most metal-poor stellar explosion ever observedwhich offers a look into the cosmic past.

This rare supernova, called 2023ufx, originated from the collapse of the core of a red supergiant star, which exploded on the outskirts of a nearby dwarf galaxy. The results of the study showed that observations of both this supernova and the galaxy in which it was discovered are low metallicity, meaning they lack an abundance of elements heavier than hydrogen or helium.

Since metals produced within supernovae inform their properties, including how stars evolve and die, learning more about their formation can tell astronomers a lot about the state of the universe when it began, especially since there were essentially no metals. around during the time of his birth, he said in a statement Michael Tucker, lead author of the study and member of the Center for Cosmology and Astroparticle Physics at The Ohio State University.

“If you want to predict how the Milky Way formed, you need to have a good idea of ​​how the first stars to explode gave rise to the next generation“Understanding that gives scientists a great example of how those early objects affected their environment.”

Dwarf galaxies in particular are useful local analogues of the conditions scientists might expect to see in the early universe. Thanks to them, astronomers know that, although the first galaxies were poor in metals, all large, bright galaxies near the Milky Way They had a long time for the stars to explode and increase the amount of metal content, Tucker said.

The amount of metals in a supernova also influences aspects such as the number of nuclear reactions it can have or how long its explosion remains bright. It is also one of the reasons why many low-mass stars are also occasionally at risk of collapsing into black holes.

The study was recently published in The Astrophysical Journal.

While the event observed by Tucker’s team is only the second supernova to be found with low metallicity, what is most unusual is its location relative to the Milky Way, Tucker said.

Typically, any metal-poor supernova that astronomers would expect to find would probably be too faint to see from our galaxy because of how far away it is. Now, due to the arrival of more powerful instruments like NASA’s James Webb Space Telescope, detecting distant metal-poor galaxies has become exponentially easier.

““There aren’t that many metal-poor locations in the nearby universe and before JWST, it was difficult to find them,” Tucker said.

But the sighting of 2023ufx turned out to be a happy accident for researchers. Newly discovered observations of this particular supernova revealed that many of its properties and behaviors are clearly different from other supernovae in nearby galaxies.

For example, this supernova had a period of brightness that remained stable for about 20 days before fading, while the brightness of its metal-rich counterparts typically lasted about 100 days. The study also showed that a large amount of fast-moving material was ejected during the explosion, suggesting that it must have been spinning very fast when it exploded.

This result implies that rapidly spinning, metal-poor stars must have been relatively common during the early days of the universe, Tucker said. His team’s theory is that the supernova probably had weak stellar winds (streams of particles emitted from the star’s atmosphere) that caused it to grow and release so much energy.

Overall, their observations lay the groundwork for astronomers to better investigate how metal-poor stars survive in different cosmic environmentsand may even help some theorists more accurately model how supernovae behaved in the early universe.