Scientists find an unusual star that hints at a new way stars can die

“Everything about it was weird,” Ji said. “Elements that you’d normally have more of, like carbon and sodium, are very low, whereas other elements like iron and zinc are very high.” 

This points to a fundamental difference in how this star came to be. It indicates it was born in the aftermath of a very different kind of explosion than scientists have previously catalogued. 

“We looked through so many types of supernova models, but nothing quite matched,” said Sanjana Curtis, formerly a postdoctoral researcher at UChicago and now at the University of California Berkeley, and the second author on the paper.

In particular, the amount of iron suggests that the star that exploded was quite massive—probably about 80 times the mass of our own sun. “But according to the best theory we have now, a star with that mass should turn into a black hole instead of exploding,” said Curtis. “So there’s no existing model yet for how this could have happened.

“It hints that we may need better theories of supernova physics, and maybe even better theories for stellar evolution itself,” she said.

Stellar archaeology

As best as the scientists can tell, the parent star probably belonged to one of the first generations of stars in the universe. After it exploded, the debris left behind eventually coalesced into a second generation of stars, one of which fell into the Milky Way, where Ji, Curtis, and their colleagues measured its makeup. 

What would this explosion have looked like? All we can tell is its elemental makeup, but Ji thinks this explosion probably looked distinctively asymmetric when it happened. “One thing we think drives massive stars to explode is energy going off in jets,” he explained. 

One thing is for sure, though—it was a very powerful explosion. 

“We think it’s possible it could have been energetic enough to blow up an entire galaxy by itself, though a small galaxy,” said Ji.

In addition to suggesting a new type of supernova, the discovery offers a tantalizing hint at that lost first generation of stars in the universe. 

“Those early stars died very quickly,” said Curtis. “Even the James Webb Space Telescope, the most powerful telescope we have, can’t see those earliest stars themselves, so that’s why we look at this second generation. It’s like archaeology for stars.” 

If scientists can find more of these unusual second-generation stars, it could help prove theories about that first generation of stars and how massive they were.

The scientists said that they began calling the oddity the ‘Barbenheimer star,’ after the popular portmanteau for the double feature of the movies Barbie and Oppenheimer, which both opened this summer at the same time the scientists were puzzling over the star that exploded. “It fits ‘Barbie’ because it’s spectacular, and ‘Oppenheimer’ because like nuclear fission, it creates new elements,” said Ji.

The authors used the UChicago Research Computing Center for the work.

Citation: “Spectacular nucleosynthesis from early massive stars.” Ji et al, Astrophysical Journal Letters, scheduled for publication Jan. 22, 2024. 

Funding: National Science Foundation, European Research Council, Australian Research Council, Hungary’s NKFI and Hungarian Academy of Sciences, DFG German Research Foundation, Max Planck Society, Carnegie Institution for Science, U.S. Department of Energy, Alfred P. Sloan Foundation (Sloan Digital Sky Survey).