What is the reason why four times the lithium of "lithium" born in Big Bang exists in outer space?

Materials that can not be used for batteries of smartphones and electric vehicleslithiumIt is thought that it was born in the big bang of the universe. Lithium, which was born by the Big Bang, has been confirmed to increase in space after that, and discussions have been made as to how lithium was born, but in recent years the cause has been clarified.

BBC - Earth - The cosmic explosions that made the Universe

The lightest lithium in the metal is the beginning of the universe that happened 13.8 billion years ago "big bangIt is thought that it was created by. The universe which was in the plasma state when the big bang occurred expands and starts to cool downBig Bang Nuclear SynthesisOccurred, and after 3 minutes from the big bang, relatively light elements such as hydrogen, helium and lithium were born.

As for the amount of primordial lithium in the early universe generated by the Big Bang, it is known that there is a large gap between estimated values ​​and theoretical values ​​calculated from the observations of the universe. Lithium with an atomic weight of 7 has only one third of the theoretical estimate, and this discrepancy is called the "cosmic lithium problem" and is known as the big mystery left by the Big Bang theory. Although the elucidation of this mystery is still continuing, it is cited the theory that it disappeared by the mutual reaction with the unknown substance "dark matter (dark matter)" thought to occupy a quarter of the universe I will.

What is the mysterious supernatant "dark matter (dark matter)" that forms the universe? - GIGAZINE

On the other hand, it is confirmed that there is a large amount of lithium in the present space in comparison with the time of the universe. Astronomers observe that a large amount of lithium is released from the surface of a relatively recently formed young star and it is presumed that lithium in the galaxy system is 150 times as heavy as the sun. By the way, this amount is about 4 times higher than the amount of lithium considered to be made in big bang. Lithium on the earth is thought to originate from a new lithium born after the birth of a big bang, but three hypotheses have been raised about where excessive lithium came from, and three factors are cited.

Cosmic ray
The first possibility is "Cosmic rays". Cosmic rays are high energy radiation centered on protons and they are flying over space. It is thought that the cosmic rays collide with substances such as oxygen that was created as the universe expands, and it was divided into lithium with smaller atomic weight.

However, Professor Brian Fields of the University of Illinois said that the lithium that was born by cosmic rays is less than 20% of the lithium in the entire universe. Since the primordial lithium that was born at the time of the big bang occurred is about 20%, the remaining 60% of the lithium seems to have another origin.

◆ AGB star
It is known that stars change shape with birth. First of all, energy is generated by nuclear fusion of hydrogen, but then the stars will continue to mass up, keeping fusion of helium, carbon and oxygen next. A star that reaches about 10 times the weight of the sun is "AGB starsIt is called the end of life in the life of the star. It is thought that this AGB star produces lithium by nuclear fusion and the lithium that is made reaches the surface of the star and is released to the universe.

◆ Novae
Also,White dwarfIt is thought that a stellar explosion called "Novae" occurs on the surface of lithium is a source of lithium. If a white dwarf is orbiting with other stars, a white dwarf with a large gravity may pull hydrogen etc. from other stars. It is thought that substances accumulated on the surface of a white dwarf separated from the star will rise in temperature and pressure, ultimately causing a nuclear fusion reaction, and lithium will be generated.

In nuclear fusion reactions, the nuclear fusion reaction occurs in a chain fashion by the heat generated, and eventually explodes as a brightly shining star that can be ascertained from the earth. This is called Nova (nova), and a lot of Nova happens to be Novae. It is thought that Novae instantaneously releases substances such as lithium to outer space with super high speed of several thousand kilometers per second.

Although the above three theories were cited, it was not clear which is a major cause of lithium production. However, in 2013, Japanese amateur astronomer Mr. Koichi Itaki discovered the nova "V339 Del" that appeared in the Makoto, and the discussion has greatly advanced. This nova V339 Del is the National Astronomical ObservatoryAkito TamamiDr. et al.'s research teamSubaru TelescopeAs a result of observation, beryllium (7 Be) with an atomic weight of 7 was detected among the released components. Because 7Be changes to lithium at half-life of 53 days, it is certain that lithium is released by Novae.

Successfully observed explosive lithium formation in space - a nova explosion was a lithium synthesis factory in space - - 20150219_sci.pdf
(PDF file)http://www.nagoya-u.ac.jp/about-nu/public-relations/researchinfo/upload_images/20150219_sci.pdf

A few months after the research presentation by Dr. Tanami et al., It is assumed that a research group in Italy detected lithium directly from another NovaAnnouncement, Making sure that lithium is generated by explosion by Novae.

Now that Novae has revealed that lithium is born, many scientists are working on quantifying how much lithium was produced by Novae. Also, there seems to be some expectation that researching the mechanism by which Novae produces a large amount of lithium in outer space may be a clue for solving the universe lithium problem that the amount of lithium at the time of the big bang is too small.

in Science, Posted by darkhorse_log