Astronomers Discover Rare Fossil of Early Stars
Astronomers Discover Rare Fossil of Early Stars
Hilo, Hawai‘i – In a groundbreaking study, a team of astronomers has discovered an ancient star bearing a unique chemical composition, unlike anything previously observed in the Milky Way Galaxy. This exceptional find bolsters theories that some of the first generation of stars in the universe included unusually massive objects.
The discovery has critical implications in understanding how the cosmos’ earliest stars were formed in the aftermath of the Big Bang. Since the first stars came to life from gas clouds containing only hydrogen and helium, their nuclear fusion and subsequent supernova explosions have played a critical role in creating a diverse array of elements.
Recent theories suggest that the inaugural stars might have included many exceedingly massive stars like 140 times more massive than the Sun, whose intense ultraviolet radiation and energetic supernovae considerably impacted the formation of the subsequent generation of stars. However, clear observational evidence for such supernovae has remained elusive.
The researchers from the National Astronomical Observatory of Japan (NAOJ), the National Astronomical Observatories of China (NAOC), and other institutions, used the Chinese survey telescope LAMOST to identify early generation stars in the Milky Way Galaxy and measured their detailed chemical compositions with the Subaru Telescope on Maunakea, Big Island of Hawai‘i.
Among 400 candidates of chemically pristine stars, they found a star called LAMOST J101051.9+235850.2 (J1010+2358) in the outer regions of the Milky Way with distinct chemical compositions produced by a pair-instability supernova – the clearest evidence yet of such supernovae.
“We believe the star, J1010+2358, we have discovered, provides the most convincing evidence that the first stars with mass larger than 100 times that of the Sun existed in the early universe,” explains Subaru Telescope assistant professor Miho Ishigaki.
“Like archaeologists excavate fossils to study an ancient history of Earth, we identify a “fossil star” in the Milky Way Galaxy and examine details of chemical patterns to know the nature of the first stars that exploded more than 10 billion years ago,” explained Professor Wako Aoki of NAOJ, who led the observing programs with the Subaru Telescope. “We are excited to find one of the strongest links between a nearby star and the extremely massive first-generation stars that only existed in the early universe.”
The focus now shifts to understanding the percentage of the first stars that were very massive – a question that can be answered by exploring more stars and measuring their chemical compositions.
These results appeared as Xing et al. “A metal-poor star with abundances from a pair instability supernova” in Nature on June 7, 2023.
About Subaru Telescope
The Subaru Telescope is an 8.2 meter optical-infrared telescope at the summit of Maunakea, Hawai‘i. It is operated by the National Astronomical Observatory of Japan (NAOJ), National Institutes of Natural Sciences (NINS). One of Subaru Telescope’s main missions, in addition to telescope operations and astronomical discoveries, is to foster education in the next generation of researchers. Subaru scientists and staff are incredibly grateful to the Hawaiian people for the opportunity of observing the universe from Maunakea, of such cultural, historical, and natural significance in Hawai‘i
