A massive young star IRS 4 heats and warps the nebula Sharpless 2-106
Credit: NASA, ESA, and the Hubble Heritage Team (STScI/AURA)
Credit: NASA, ESA, and the Hubble Heritage Team (STScI/AURA)
Once thought to be a pure descendant of one the universe’s first stars, new research on star J1010+2358 uncovers a more complex history.
The First Stars and Their Violent Ends
During the universe’s debut into star formation, only hydrogen, helium, and some lithium existed. Without metals (i.e., elements heavier than helium) to efficiently cool the gas, the first generation of stars, called Population III stars, likely formed with much higher masses than any subsequent generation. Based on theoretical modeling, Pop III stars may have had masses hundreds of times the mass of the Sun; however, their true mass distribution is still under investigation.
Some of the most massive Pop III stars likely ended their lives in pair-instability supernovae (PISNe), a type of supernova so energetic and violent it completely rips the star apart, leaving behind no stellar remnant. Metals that formed inside these stars and within their explosions are released into the interstellar medium, creating a newly enriched cosmic soup that fuels the next generation of star formation. Finding stars born out of PISN material, and particularly descendants whose chemical signatures trace back to a single Pop III star, is no simple task, but this detection would provide powerful information about the first stars in the universe.
Some of the most massive Pop III stars likely ended their lives in pair-instability supernovae (PISNe), a type of supernova so energetic and violent it completely rips the star apart, leaving behind no stellar remnant. Metals that formed inside these stars and within their explosions are released into the interstellar medium, creating a newly enriched cosmic soup that fuels the next generation of star formation. Finding stars born out of PISN material, and particularly descendants whose chemical signatures trace back to a single Pop III star, is no simple task, but this detection would provide powerful information about the first stars in the universe.
Measured chemical abundance pattern of J1010+2358 (red stars). Multiple model predictions are overlaid; the dashed gray line shows a 100% 260-solar-mass PISN contribution, indicating an ill fit to the data. Credit: Skúladóttir et al. 2024
Likely Origins of J1010+2358
How, then, did J1010+2358 obtain its interesting chemical composition? Through applying theoretical models for various progenitor combinations, Skúladóttir’s team found a best fit where the star’s metals come from a combination of a 13-solar-mass second-generation star that underwent a core-collapse supernova and a 39-solar-mass Pop III core-collapse supernova. They considered multiple scenarios with the star obtaining some of its metals from a 260-solar-mass PISN, but all plausible fits have PISN contributions too low to further characterize the mass distribution of first-generation stars.
Measuring Chemical AbundancesWith a low metallicity and unique chemical abundance pattern, the star J1010+2358 was initially suggested to have been formed from the gaseous remains of a single 260-solar-mass Pop III star. However, more recent analysis suggests that the star’s origins are more ambiguous, perhaps obtaining only 10% of its metals from such a PISN.
To more confidently determine J1010+2358’s ancestry, a team led by Ása Skúladóttir (University of Florence) used the Ultraviolet and Visible Echelle Spectrograph on the European Southern Observatory’s 8.2-meter Very Large Telescope to derive a more detailed abundance pattern of the star. They found the carbon and aluminum abundances to be significantly higher than predicted for pure PISN descendants. The team also remeasured a number of other elements, and the results further signal that J1010+2358 is not a descendant of a single, massive Pop III star as previously claimed.
To more confidently determine J1010+2358’s ancestry, a team led by Ása Skúladóttir (University of Florence) used the Ultraviolet and Visible Echelle Spectrograph on the European Southern Observatory’s 8.2-meter Very Large Telescope to derive a more detailed abundance pattern of the star. They found the carbon and aluminum abundances to be significantly higher than predicted for pure PISN descendants. The team also remeasured a number of other elements, and the results further signal that J1010+2358 is not a descendant of a single, massive Pop III star as previously claimed.
Quality of fit results for J1010+2358 containing two progenitors, with one being a PISN of a given mass and fraction of metal contribution and the other being a 13-solar-mass second-generation star that underwent a core-collapse supernova. Values 2 and below are best quality fits and most plausible progenitor scenarios. Click to enlarge. Credit: Skúladóttir et al. 2024
Likely Origins of J1010+2358
How, then, did J1010+2358 obtain its interesting chemical composition? Through applying theoretical models for various progenitor combinations, Skúladóttir’s team found a best fit where the star’s metals come from a combination of a 13-solar-mass second-generation star that underwent a core-collapse supernova and a 39-solar-mass Pop III core-collapse supernova. They considered multiple scenarios with the star obtaining some of its metals from a 260-solar-mass PISN, but all plausible fits have PISN contributions too low to further characterize the mass distribution of first-generation stars.
Stars have complex histories stored within their chemical DNA, and the difficulty of identifying a star with a single first-generation predecessor underscores the importance of careful chemical abundance analyses. Although J1010+2358 is likely not a true PISN descendant, the lessons learned through this star will be critical in the quest to uncover the properties of the universe’s first stars, and upcoming high-resolution spectroscopic surveys may reveal more promising candidates in the near future.
Stars have complex histories stored within their chemical DNA, and the difficulty of identifying a star with a single first-generation predecessor underscores the importance of careful chemical abundance analyses. Although J1010+2358 is likely not a true PISN descendant, the lessons learned through this star will be critical in the quest to uncover the properties of the universe’s first stars, and upcoming high-resolution spectroscopic surveys may reveal more promising candidates in the near future.
By Lexi Gault
Citation
“On the Pair-instability Supernova Origin of J1010+2358,” Ása Skúladóttir et al 2024 ApJL 968 L23.
doi:10.3847/2041-8213/ad4b1a
doi:10.3847/2041-8213/ad4b1a
Editor’s Note: Lexi Gault is a fourth-year graduate student at Indiana University who was recently selected as the 2024–2025 AAS Media Fellow. We’re excited to welcome Lexi to the team and look forward to featuring her writing on AAS Nova regularly!
