Ancient stars have been discovered orbiting near the center of the Milky Way galaxy. The stars may have formed in just one billion years of the universe’s birth.
In general, old stars are only found in the 150-plus globular clusters (also known as “galactic wanderers” and possibly related to supermassive stars) on the edge of the Milky Way.
Previously held at Cardiff University in Wales, UKNational Astronomy Meeting 2023An international research team, the Pristine Inner Galaxy Survey (PIGS), whose findings were published in , focused on the center of the Milky Way galaxy. Models of galaxy formation suggest the presence of ancient stars there, but so far few have been discovered. Because the ancient stars at the center of the galaxy are covered in dust and outnumbered by young stars, they are difficult to identify.
An artist’s impression of the ancient stars at the center of the Milky Way galaxy. The left figure shows the orbits of several stars. The image to the right shows its position relative to the Sun in the Milky Way galaxy and its slow rotation. (LEFT BACKGROUND – ESA/GAIA, ARTIST IMPRESSION: AMANDA J. SMITH AND ANKE ARENTSEN, INSTITUTE OF ASTRONOMY, CAMBRIDGE)
Legacy of the early universe
But those ancient stars are very different from young stars. Young stars, like our Sun, are made up of all sorts of heavy elements (oxygen, carbon, iron, etc.) from supernova explosions, whereas ancient stars formed before they were rich in those elements. It is composed mainly of hydrogen and helium.
The PIGS study found that the ancient stars were likely born in chaos, but were in gradual motion.
“It’s exciting to think that we’re seeing stars forming in the earliest stages of the Milky Way galaxy, which has been largely untouched until now,” said PIGS member Dr. Anke Arentsen of the University of Cambridge.say. “These stars likely formed within a billion years of the Big Bang, so they are a legacy of the early universe.”
key to galaxy formation
This largest and most detailed observation of the early inner galaxy was made using the Canada-France-Hawaii Telescope (CFHT) in Mauna Kea, Hawaii, and confirmed using the Anglo-Australian Telescope at Siding Spring Observatory, Australia. .
That data has since been combined with data from the Gaia program to see how ancient stars move in the Milky Way galaxy. It should help us understand what all galaxies looked like when they began to form.
The Big Bang is a dominant theory to explain how the universe was created. It is thought to have occurred 13.8 billion years ago and marked the beginning of the expansion of a hot, dense fireball into the universe we see today.
Globular clusters are dense spheres of hundreds of thousands of stars of similar age that are thought to have formed at the same time as the first galaxies, shortly after the Big Bang.
