'Barbenheimer': Study finds clues of ancient explosion in an extant star

In a remote corner of the cosmos, a colossal star underwent a supernova explosion, and the distinctive chemical imprints from this celestial event have been transmitted to a star within our Milky Way galaxy. The existing star, dubbed J0931+0038, has a strange chemical makeup that can only be linked to the leftovers of a huge stellar predecessor.

“We’ve never seen anything like this,” said Alex Ji of the University of Chicago, who led this study. “Whatever happened back then, it must have been amazing. We nicknamed it the ‘Barbenheimer Star’ for its spectacular nucleosynthesis,” added Ji. This massive ancient Barbenheimer star had at least 50 to 80 times the mass of our Sun.

This supernova has left an indelible trail of elemental remnants, offering a glimpse into a celestial spectacle that unfolded billions of years ago. The unusual presence of elements The team was able to track the element trail with the help of the Sloan Digital Sky Survey (SDSS). SLOAN first captured an image of this extant bright red star J0931+0038 in 1999.

Two decades later, the SDSS telescope revisited the star, employing advanced technicolor observations through the SDSS Milky Way Mapper program. This time, the focus was on the star's spectrum, which revealed important details about its temperature and chemical makeup. Surprisingly, the spectrum data revealed extremely low levels of magnesium.

The team decided to further dig up the unusual chemistry using the Magellan telescopes in Chile. The followup spectrum data revealed a celestial enigma – the Barbenheimer Star – with distinctive features setting it apart from any other observed star. As per the , the data revealed “low abundances of elements with odd numbers on the periodic table like sodium and aluminum.” On the other hand, the observations found a significant presence of elements near iron, including nickel and zinc, and a high concentration of heavier elements like strontium and palladium.

“We sometimes see one of these features at a time, but we’ve never before seen all of them in the same star,” said Jennifer Johnson of the Ohio State University, one of the members of the stellar archaeology team. The team suggests that the star's unusual chemistry indicates that it formed from supernova leftovers.

The celestial body we see now contains the remains of an old and unusual star. The team suggests that the star's unusual chemistry indicates that it formed from supernova leftovers. This means that the celestial body we see now contains the remains of an old and unusual star. The findings have been accepted for publication in the and are currently available on .

Stars formed with initial mass over 50 Msun are very rare today, but they are thought to be more common in the early universe. The fates of those early, metal poor, massive stars are highly uncertain. Most are expected to directly collapse to black holes, while some may explode as a result of rotationally powered engines or the pair creation instability.

We present the chemical abundances of J0931+0038, a nearby low mass star identified in early followup of SDSS V Milky Way Mapper, which preserves the signature of unusual nucleosynthesis from a massive star in the early universe. J0931+0038 has relatively high metallicity ([Fe/H] = 1.76 +/ 0.13) but an extreme odd even abundance pattern, with some of the lowest known abundance ratios of [N/Fe], [Na/Fe], [K/Fe], [Sc/Fe], and [Ba/Fe].

The implication is that a majority of its metals originated in a single extremely metal poor nucleosynthetic source. An extensive search through nucleosynthesis predictions finds a clear preference for progenitors with initial mass > 50 Msun, making J0931+0038 one of the first observational constraints on nucleosynthesis in this mass range.

However the full abundance pattern is not matched by any models in the literature. J0931+0038 thus presents a challenge for the next generation of nucleosynthesis models and motivates study of high mass progenitor stars impacted by convection, rotation, jets, and/or binary companions. Though rare, more examples of unusual early nucleosynthesis in metal poor stars should be found in upcoming large spectroscopic surveys..