Ancient stars born during the Cosmic Dawn have been identified in the center of the Milky Way.
As part of a study to find some of the oldest known stars in the Universe, scientists took a closer look at the oldest, but faintest stars, and found that the orbits between galaxies are unstable, regardless of the star. confusion around them.
The findings, led by astronomer Anke Arentsen from the University of Cambridge in the UK, have been presented at the annual National Astronomy Meeting in the UK.
We can tell how old a star is by the amount of metal in it. When the first stars in the Universe formed, they had to build themselves from the basic elements that were available at the time – mainly hydrogen and helium. But the nuclear reactors burning inside began fusing hydrogen atoms into heavier elements, from helium to iron.
Then, after exploding in a degenerate supernovae, they seeded these heavy elements into space, and the heavier elements formed in the secondary supernova processes. Then the stars began their life with very rich material. The younger the star, the more metal it contains.
In the example, while there are still stars, something is happening. We’ve found several “massive” stars floating around the Milky Way Galaxy, but mostly outside, it’s a galactic halo. Astronomers think that the oldest stars must be in the center of the galaxy, but because this region is rich in metals, and there is a lot of dust that blocks our view, it is difficult to find them.
Anke and his colleagues started a project called the Pristine Inner Galaxy Survey (PIGS) to try to find them. By measuring the amount of light coming from a particular star, astronomers can find wavelengths that are amplified or shortened by the presence of certain objects. They looked for the initial signature associated with stars that are the least dense in metals, and identified about 8,000 of them.
Later observations confirmed that it was made up of iron-free stars, making it about 1,300 ancient stars in the galactic center. Because they found so much, the researchers were able to conduct population studies.
They used data from the Gaia observatory, which is an ongoing project to map the three-dimensional location and movement of stars in the Milky Way. With this, researchers were able to determine the galactic paths of their ancient stars.
Arentsen and his colleagues found that the motion of ancient stars around the center of the galaxy is slow.
In addition, ancient stars have irregular orbits, but still have a narrow orbit between galaxies.
Finally, the orbits of the stars are usually confined to the interior of the galaxy. Even stars in orbits tend to stay in the central region of the Milky Way.
“It is exciting to think that we are seeing stars that started to form in the early stages of the Milky Way Galaxy, which were previously inaccessible. “Arensen said.
“The available data on these ancient objects is growing rapidly. I am excited to see what we will learn about these first stars to discover our Galaxy in the next few years!”
You can track the team’s findings about these ancient stars on the preprint server arXiv.