Strange star holds 'holy grail' clues about unique supernova explosions in the early universe

According to a recent research, the chemical signatures of the star are proof that the earliest big stars produced pair-instability supernovae.

According to a recent research, the odd star's chemical makeup in the Milky Way galaxy's halo provides the first proof of the catastrophic deaths of the universe's initial stars.

Around 100 million to 250 million years after the Big Bang, which happened roughly 13.8 billion years ago, the universe's first stars were formed. However, it is still unknown to scientists how this initial generation of stars' mass was dispersed.

According to early universe star models, some of these celestial bodies may have possessed masses that were equal to hundreds of suns. Stars with masses between 140 and 260 times that of the sun back then would have ended their lives in supernova blasts different from those typically seen in the later universe (known as Type II and Type Ia supernovae), according to study team members. Massive stars end their lives in enormous cosmic explosions called supernovae. Pair-instability supernovae (PISNe) are the name given to these unusual outbursts.

Astronomers refer to the elements heavier than hydrogen and helium as metals, and all supernovae disperse these elements across the cosmos. Giant star cores produce metals, which are then absorbed into the following generation of stellar bodies.

These PISNe should leave behind a distinctive chemical imprint on the following generation of stars since they differ significantly from typical explosive stellar death throes. However, up to this point, astronomers have not found these cosmic fingerprints.

In the latest study, a group of researchers discovered that the chemically odd star LAMOST J1010+2358 may be the first sign of PISNe in early massive stars.

LAMOST J1010+2358 formed in a gas cloud that was dominated by the remnants of a 260 solar-mass star that died in a PISNe blast, according to research using data from the Large Sky Area Multi-Object Fiber Spectroscopic Telescope (LAMOST) survey and follow-up observations by the Subaru Telescope in Hawaii.

The team's analysis of the chemical composition revealed that sodium and cobalt were exceedingly rare and that there was a wide range between elements with odd and even numbers of electrons.

This is important because PISNe are generated by an instability brought on by the generation of electron and anti-electron pairs, also known as positrons. This instability causes a highly large star's core thermal pressure to drop and causes a partial collapse.

According to research co-author Zhao Gang, a professor at the National Astronomical Observatories of the Chinese Academy of Sciences (NAOC), "it provides an essential clue to constraining the initial mass function in the early universe." Before this study, the metal-poor stars had not shown any signs of supernovae from such big stars.

The scientists also discovered that LAMOST J1010+2358 has a substantially higher iron content than other metal-poor stars in the galactic halo that are the same age. This implies that second-generation stars formed in clouds containing PISNe's gaseous remnants may have more heavy elements than previously assumed.

Finding proof of these early pair-instability supernovae is one of the holy grails of looking for metal-poor stars, according to astronomer and former Harvard University astronomy department head Avi Loeb, who was not involved in the study.

The team’s research is detailed in a paper published online today (June 7) in the journal Nature.