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Oldest known stars in the galaxy, found in the bulge of the Milky Way

  Astronomers look for fossils of an early universe stuffed in the extension of the Milky Way

New research shows that the cluster of stars HP1 (here through the South Chili Gemini South Telescope) contains some of the Milky Way's oldest stars which can count to about 1

2.8 billion years old.

Photo credits: Gemini Observatory / AURA / NSF; composite image produced by Mattia Libralato of the Space Telescope Science Institute

. Astronomers looked into the gloomy bulge of the Milky Way and found some of the oldest known stars in the universe.

In a study to be published in the April 2019 issue of the Monthly Notices journal of the Royal Astronomical Society, the researchers analyzed a cluster of old, faint stars called HP1, located some 21,500 light-years from Earth inside the central bulge of our galaxy is located. Based on observations from the South China Gemini telescope and the Hubble space telescope data from the archives, the researchers calculated the age of the stars at about 12.8 billion years. This makes them one of the oldest stars ever discovered in the Milky Way or throughout the universe.

"These are also some of the oldest stars we've ever seen," said co-author of the study, Stefano Souza, a graduate student at the University of São Paulo, Brazil, in a statement. [15 Unforgettable Images of Stars]

The bulge of the Milky Way – a bulbous, 10,000 light-bright area of ​​stars and dust leaking out of the spiral disk of the galaxy – is said to contain some of the galaxy's oldest stars.

Previous studies have attempted to prove that ancient stars hid in the Milky Way bulge by examining HP1 and other nearby clusters. Souza and his colleagues, however, analyzed the problem with an unprecedented resolution thanks to an imaging technique called Adaptive Optics, a technique that corrects images of outer space for light distortions caused by the Earth's atmosphere.

By combing these ultra-high-resolution observations and Hubble archival footage, the team calculated the distance to Earth even for the darkest and dustiest stars in HP1. These intervals helped the team calculate the brightness of each star. The intensity and color of the light of each star in turn shows the star type – whether it is a dwarf or a giant, for example, or it emits many elements heavier than hydrogen and helium.

The weight of a The elements of the star – also called "metallicity" – are important information for scientists who are concerned with the aging of celestial bodies. The researchers suspect that the first stars of the universe were formed from primeval clouds of pure hydrogen gas. It is believed that the first helium atoms in the Universe emerged from the nuclear reactions in the hearts of these ancient stars. As more and more stars were born, all the other elements known to humans exploded.

Stars that produce Many elements that are heavier than hydrogen and helium are therefore considered relatively young in the cosmic scheme of things. When the twin researchers discovered that the stars of HP1 were extremely heavy, they knew they were targeting an old cluster.

The team calculated that the stars probably date to the first billion years of the universe "They are about 12.8 billion years old."

"HP 1 is one of the surviving members of the fundamental building blocks that make up the galaxy's inner bulge," said Leandro Kerber of the University of São Paulo and the Brazilian State University of Santa Cruz, the statement said.

The fact that the Milky Way hides age-old stars in its domed middle section means the area is the perfect place to study the awkward childhood years of our galaxy. Live Science .

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