A rare type of supernova among the first stars in the Universe

Scientists have studied the chemical composition of a very old star. They found out that it was formed in a gas-dust cloud that remained after the first generation of luminaries. They exploded as a rare type of supernova: pair-instability and were very massive.

There was a rare type of supernova in the early Universe. Source: NAOC

Chemical composition of an old star

A new study by scientists from the Chinese Academy of Sciences showed that among the first stars that existed in the Universe there were many real giants, which mass reached from 140 to 260 solar masses. They exploded as a rare type of supernova.

Such thoughts of scientists were prompted by the study of the star LAMOST J1010+2358. They found it thanks to the Large Sky Area Multi-Object Fiber Spectroscopic Telescope (LAMOST) sky survey data, and then further studied it using the Subaru telescope spectrograph.

The star is very old and almost certainly belongs to the luminaries of the second generation. Its chemical composition has a number of features. First of all, this concerns the extremely low content of sodium and cobalt. The ratio of sodium to iron is almost 100 times lower than that of the Sun.

In addition, the chemical composition shows a strange difference in the content of chemical elements with even and odd numbers in the periodic table, for example sodium/magnesium and cobalt/nickel. And this result correlates well with the results of three physical models at once, therefore, scientists already know what they have found.

Rare type of supernova

Scientists believed that LAMOST J1010+2358 was formed in a gas-dust cloud, which was enriched with the remnants of a rare type of supernova explosion. Previously, scientists suspected that the first stars were very massive. It was recently proven that they were not born alone. And new evidence said that they were huge.

The characteristic content of chemical elements in LAMOST J1010+2358 corresponds to the theoretically predicted for pair-instability supernovae. These are very unstable stars with low metallicity. Gamma radiation in their depths is so intense that electron-positron pairs are born.

This reduces the light pressure on the outer layers, as a result of which the balance between it and the forces of attraction is disturbed. The star begins to fall into itself, but at some point the birth of pairs of particles stops and the star explodes.

At the same time, it does not leave behind a white dwarf, a neutron star, or a black hole. Instead, it just throws a huge amount of iron and other heavy elements into space. Now there are almost no such large luminaries to implement this scenario.

However, as the study showed, there were significantly more such luminaries in the early Universe. However, this gives scientists the opportunity to make another interesting discovery. Previously, it was believed that the early generations of stars were almost completely devoid of heavy elements. However, they are still present in LAMOST J1010+2358, although in an unusual combination. Apparently, this happened precisely thanks to the pair-instability supernovae.

According to phys.org

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