Early Universe’s stars had up to several hundred solar masses. The earliest stars of 140-260 solar masses became pair-instability supernovae (PISNe). These stellar explosions would have left a unique chemical signature in the atmosphere of next-generation stars that is quite unlike that of Type II and Type Ia supernovae. But there was no sign of this signature — until now. In a new study, astrophysicists show that LAMOST J1010+2358, a very metal-poor in the Galactic halo, is clear evidence of PISN from very massive first stars in the early Universe.
“Our study provides an essential clue to constraining the initial mass function of stars in the early Universe,” said Monash University’s Professor Alexander Heger.
“Before this study, there was no evidence of PISN in the first generation of stars.”
LAMOST J1010+2358 was identified as a very metal-poor star by the Large Sky Area Multi-Object Fiber Spectroscopic Telescope (LAMOST) survey.
Using the Subaru telescope, Professor Heger and colleagues conducted a follow-up high-resolution spectroscopic observation of the star.
They were able to calculate abundances for over ten elements in LAMOST J1010+2358.
They found that the star has low sodium and cobalt abundances; its sodium-to-iron ratio is below 1/100 that of the Sun.
LAMOST J1010+2358 also has a big difference in the abundance of elements with odd and even charge numbers, like sodium, magnesium, cobalt, and nickel.
“Sodium, magnesium, cobalt, and nickel abundances show a pattern unique to PISNe,” Professor Heger said.
“The peculiar odd-even variance, along with deficiencies of sodium and α-elements in this star, are consistent with the predicted chemical fingerprint of primordial PISN from first-generation stars with 260 solar masses.”
According to the astronomers, LAMOST J1010+2358 is clear evidence of PISN supernovae.
“This type of supernova is due to a hydrodynamical instability caused by electron-positron pair formation at the end…
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