Exceptional star is the most pristine object known in the universe

A relatively nearby star, in which, in the visible, there is not enough almost any of the heavy elements produced by Supernovae, can be a direct descendant of the very first stars that formed in the universe.

Astronomers think The first stars They were composed only of hydrogen and helium, which floated around the Big Bang. Only when these stars ended in fuel and exploded in Supernova, which was more heavy than helium. The remainder, the gas rich in elements from these original explosions, then formed the next generation of stars, and the cycle was repeated to ultimately create all the elements that we see in stars and planets today.

Most of the stars that we see in our galaxy are many generations removed from this initial population of stars, but some astronomers called “Star archaeologists“Found the stars that Almost untouchedThe field is believed that they are the stars of the “second generation” born of the remains of the earliest stars.

Now, Alexander Ji At the University of Chicago and his colleagues, a star was found, which has the lowest total number of “metals”, which for astronomers means all elements except hydrogen or helium, in the World Universe. The star, called SDSS J0715-7334, is located in a large cloud of Magellanic, a satellite galaxy of the Milky Way and has a metal content of about 0.8 parts per million, which is about 20,000 times less than that of our Sun.

After having first discovered a star in Sloan Digital Sky Survey from an unusually low metal, Ji and his colleagues watched him with the Magellan telescope in the Las Campanas observatory in Chile. They found that the star contains an extremely low amount of iron comparable to those that are observed in other almost untouched stars. Nevertheless, they found that it also has an extremely low amount of carbon, at levels that we do not see in the stars from the Milky Way.

“This is a rather cool discovery, but [in terms of iron levels] This is a little more extremely than some other examples that we have already found, ”says Anke Ardern Arentsen At the University of Cambridge. “But what is especially interesting is that the majority [nearly] The untouched stars, which we know about, have a lot of carbon, while this does not have. ”

This may assume that this is formed in a completely different way from the almost initial stars that we see in the Milky Way, says Anna Frebblel In the Massachusetts Technological Institute.

To make a star the size of the SDSS J0715-7334, you need a relatively small and cool gas warehouse, which usually requires heavier elements with high-energy electrons, such as carbon so that gas can lose enough energy. But almost the absorption of carbon in the star would have difficulty cooling, as it is.

One of the few alternative explanations is that instead there was a cloud of cosmic dust, consisting of heavier elements that helped him cool, a mechanism that we do not see so early in the history of the Universe, at least in our own galaxy.

“The question arises, various environments in different places in the universe cool their gas in the early time?” Fribel says. “We can ask the question why they cool him in the other way, but I don’t think we have a good answer to this.”

World capital of astronomy: Chile

Astronomic main points of Chile. Visit some of the most technologically advanced observatories in the world and Stargaze under some of the cleanest sky on earth.