Friday , April 16 2021

They find the brightest star on the Milky Way



Astronomers have discovered a star with the lowest concentration of iron and other heavy elements. This discovery allows us to learn more about the processes occurring in the early Universe and its chemical evolution.

A group of astronomers led by Thomas Nordlander announced the discovery of the star SMMS 1605-1443. Gabriel Perez Diaz / CMM (IAC)

Astronomers have discovered a star with the lowest concentration of iron and other tough elements that have not yet been defined. This discovery allows us to learn more about the processes occurring in the early Universe and its chemical evolution. The preprint of the article is available onl site arXiv.org.

In astrophysics, metals refer to those elements heavier than hydrogen and helium. At the beginning of the Universe, the first stars consisted only of these two "light" elements, as well as a small amount of lithium and beryllium. Later, in the depths of celestial bodies, the formation of more severe elements occurs, which in the final phases of their evolution fell into the interstellar medium. (Read: How is it possible to take a picture of something that does not even avoid light?)

The stars of the next generations contain an increasing number of metals. Therefore, the search for stars and galaxies with low levels of metallicity is an important task to understand the processes occurring in Early universe.

The content of a metal in a star is defined as the difference between the logarithms of the ratio of the concentration of iron atoms and hydrogen atoms in the star and the sun. In this case, the level of metallicity of the Sun is taken as conditionally zero. For the ancient stars, the value of [Fe/H] is between -2 and -1, which means that the content of the heavy elements in them is smaller than in the Sun, 10-100 times.

The metal star is considered to be the poorest star of the SMSS J0313-6708, roughly 13.6 billion years ago, which is estimated to have an upper limit of metallicity lower than -7.3. The poorest iron stars for which are fairly accurate estimates of metallicity are HE 1327-2326, HE 0107-5240 and SD 1313-0019, whose Fe / H values ​​are -5.7, -5.4 and -5 respectively.

Anemic star

Now, a group of astronomers led by Thomas Nordlander announced the discovery of the star SMSS 1605-1443, which is characterized by being an ultra-fast star, with the lowest concentration of iron ever detected. It is located in the halo of the Milky Way, 36 thousand light-years from Earth, and its astral follow-up is possible thanks to SkyMapper telescope. Later, SMSS 1605-1443 was studied with the WIFES spectrograph installed in the ANU telescope 2.3 meters, and MIKE spectrograph installed in one of the Magellan telescopes of 6.5 meters. (You may be interested in: Astronomers accurately determine the true mass of the Milky Way.)

Comparison of content values ​​of chemical elements (blue squares) and upper bounds of their content (blue arrows) in a star with data from simulations of supernova explosions from generation III. / T. Nordlander et al./arXiv: 904.07471 [astro-ph.SR]

SMSS 1605-1443 is the star of the red giants, with an effective temperature of approx 4.850 degrees Kelvin Your value of [Fe/H] is -6.2, which is the lowest value ever determined. At the same time, the star is rich in carbon ([C/Fe] = 3.9), as well as in calcium, magnesium and titanium, elements born during the α process.

On an abundance of elements formed during the processes р о с. It is assumed that its composition is enriched with low-mass supernovae of the population III (about 10 sun masses): a pinch of the monstrous source the basic material of the Big Bang. Additional observations of this star will allow for more detailed chemical analysis and an understanding of its genesis.

Some celestial bodies are more complex than others. But they are all unique in composition and behavior, opening mysterious and unrepeatable boxes for Pandora. Previously, specialists analyzed a star with an alien mega-structure: red dwarf with unusual darkening patterns; while another group of astronomers have discovered that Proxima Centauri, the closest star of our solar system, can dominate the icy world six times larger than the Earth. (You may be interested in: The Milky Way is bigger than we thought)


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