Astronomers have discovered what could be one of the oldest stars of the alliance, a body that was almost entirely from materials released from Big Bang.
The discovery of this about 13.5 billion years old tiny stars means several stars with very low mass and very low metallic content, probably there, perhaps even some of the first stars of the star.
The star is unusual because, unlike other stars with very low metal content, this part of the "thin disk" of the Milky Way-part of the galaxy in which our sun lives.
And since this star is so old, researchers say that it is possible that our galactic neighborhood is at least 3 billion years older than the previous one. Findings are published in Astrophysical journal.
"This star is perhaps one in 10 million," said lead author Kevin Schlaufman, Johns Hopkins University, assistant professor of physics and astronomy. "He told us something very important in the first generations of stars."
The first stars of the Big Bang universe would be entirely composed of elements such as hydrogen, helium and small amounts of lithium. Those stars produced elements that were heavier than helium in their nuclei and seized the universe when they exploded as supernovae.
The next generation of stars was created from the clouds of material surrounded by these metals and incorporated into make-up. The metal content or metal star in space increased as the aging and death cycle continued.
The newly discovered star is an extremely low metal, indicating that in a cosmic family tree, it could only depart from one generation from the Great Threshold. Indeed, this is the new record holder for the star with the smallest complement of heavy elements – it has about the same difficult content as the Mercury planet. In contrast, our sun has thousands of generations on this line and has the content of heavy elements equal to 14 Jupiters.
Astronomers found around 30 old "ultra-metal-poor" stars with approximately the mass of the sun. Star Schlaufman and his team found that only 14 percent of the mass of the sun.
The star is part of a two-star system that circles around the common point. The team found a small, almost invisibly weak "secondary" star after another group of astronomers discovered a much lighter "primary" star. This team measured the primary composition by exploring the high-resolution optical spectrum. The presence or absence of dark lines in the starry spectrum can identify the elements it contains, such as carbon, oxygen, hydrogen, iron, and others. In this case, the star has an extremely low metal composition. These astronomers also found out unusual behavior in the star system, which meant the presence of a neutron star or black hole. Schlaufman and his team found that they were wrong, but discovered a smaller companion of the visible star.
The existence of a smaller accompanying star proved to be a great discovery. Schlaufman's team is able to conclude its weight by examining the light "vibrating" of the primary star when the gravity of a small star drags on.
Already in the late 1990s, researchers believed that only the mass stars appeared in the earliest stages of the universe – and that they would never be noticed because they burn fuel and die so quickly.
But when astronomical simulations became more sophisticated, they began to suggest that in certain situations there could still be a star of this period of very low mass, even more than 13 billion years from the Big Threshold. Unlike large stars, those with low mass can live very long. Red dwarf stars, for example, with a part of the mass of the sun, should live in trillions of years.
The discovery of this new ultra-fine metal star, called 2MASS J18082002-5104378 B, opens up the possibility of observing even older stars.
"If our conclusion is correct, then small stars with the composition can be exclusively the result of Big Bang," said Schlaufman, who is also associated with the University Institute for Data Intensive Engineering and Science. "Although in our galaxy we have not yet found this object, it can exist."
A rare star opens the window at the beginning of the time
Kevin C. Schlaufman et al., A star that is a weak metal near hydrogen, Astrophysical journal (2018). DOI: 10.3847 / 1538-4357 / aadd97