Newborn stars are estimated to be born when the universe is about 100 million years old, which is less than 1% of the current cosmic year. The first generation of stellar astrophysics is also known as stellar group III (classified according to the metal abundance ratio, stellar group I is like the sun; stellar group II is common in old stars in globular clusters, with less metal content; stellar group III The abundance of other metals is lower except for hydrogen and helium). Astrophysical theories believe that the large mass of the first generation of stars caused the stars’ life cycle to reach a supernova explosion, and the blasted elements would be scattered in interstellar space. However, astronomers have been searching tirelessly for decades, they have not found direct evidence of the existence of newborn stars.
In the new findings, published in The Astrophysical Journal, astronomers used a near-infrared spectrometer to observe several of the most distant known quasars at one of the Gemini Observatory’s 8.1-meter-diameter telescopes. By analyzing the spectra of the gas clouds around the quasar, they found an unusual composition: 20 times more iron than the Sun, and a surprisingly low ratio of magnesium to iron (Mg/Fe).
Scientists believe this feature is left over from the first generation of stars that exploded in a pair-instability supernova type. It is estimated that the star is about 150 to 250 times the mass of the sun as a giant star. Unlike other supernovae, they don’t leave debris (like a neutron star or black hole) in place, but instead throw all matter out. Therefore, to find the method of the first generation of stars, the first is to observe this type of explosion event by chance (it is extremely difficult to encounter it); the second is to use the chemical characteristics of elements to identify the material ejected into interstellar space. But this is also a tricky job, because the spectral brightness not only represents element abundance, but also contains other physical parameters, which need to be carefully calibrated.
In search of proof of the existence of Massive Star Population III, several years ago astronomers focused on stars in the Milky Way’s halo to try to answer the mystery. This time from the spectral element wavelengths of quasars, using intensities to estimate element abundances, published by Yuzuru Yoshii and Hiroaki Sameshima of the University of Tokyo and other co-authors: “A star with a mass of about 300 solar masses blasts magnesium iron in an unstable pair supernova The ratio is consistent with our elemental analysis of the quasar observed in this time.” This is an exciting result, indicating that this method can be used to find newborn stars.
Although the massive star III is no longer in the universe today, the matter left in interstellar space may still exist to this day. To more thoroughly explain the new findings, observations from more sources are needed to investigate whether there are similar characteristics. If this new tool for finding the first stars is identified, we will be able to sort out the details of the evolution of the universe more clearly.
(This article is reproduced with permission from the Taipei Planetarium; the first image is an artist’s impression of a massive star III in the early universe. Source: NOIRLab / NSF / AURA / J. da Silva / Spaceengine)
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