An international team of scientists has discovered a group of relic stars in the core of the Milky Way, slowly orbiting the center of the galaxy. The results of the study were presented at the National Astronomy Meeting 2023 at Cardiff University. The press release was published on Phys.org.

The observations were made as part of the Pristine Inner Galaxy Survey (PIGS) astronomical service, which aims to provide the most complete description of ancient, metal-poor stars in the center of the Milky Way. Astronomers used the Canada-France-Hawaii Telescope (CFHT) on Mauna Kea in Hawaii to select candidate stars. Later, the nature of the objects was confirmed by spectroscopic observations made using Australia’s AAT telescope (Anglo-Australian Telescope).

The resulting data was combined with data from the Gaia space telescope to determine how these stars moved along the Milky Way. It turns out that the older the stars, the more chaotically they move, but in general they all revolve around the center of the galaxy. Many spend most of their lives in the inner regions of the galaxy, a conventional sphere whose radius reaches only half the distance from the center of the Milky Way to the Sun.

These stars are mostly composed of hydrogen and helium and contain much less heavy elements than younger stars like the Sun. Some of the detected stars were born within the first billion years after the Big Bang, so they are “traces” of processes that took place during the formation of galaxies.