The most comprehensive collection of observations of the oldest stars in the Milky Way, the center of our galaxy, has been made by an international team of researchers. Despite being thought to have formed chaotically, the Pristine Inner Galaxy Survey (PIGS) team discovered that this group of stars is slowly spinning around the Milky Way’s center. They also appear to spend the majority of their long lives close to the center of the galaxy. Dr. Anke Arentsen, a member of the PIGS team from Cambridge, will present the new findings this week at the University of Cardiff’s National Astronomy Meeting 2023.
It is possible to use some of the stars that formed in the first billion years after the Big Bang to examine how galaxies formed. These stars are still in existence today. They can be distinguished from younger stars like the Sun by their pristine chemical composition, which consists primarily of hydrogen and helium and has a much lower abundance of heavier elements. These ancient stars are typically sought out in the low-density halo surrounding our galaxy, away from the disk plane of the Milky Way.
World arrangement models recommend that the extremely most established stars are supposed to be available in the thick inward pieces of the Smooth Way. Finding them in this district is difficult as our view of the focal point of the Universe is impeded by a lot of interstellar residue, and old stars are very uncommon compared with by far most of their more youthful companions.
Arentsen and her team used a unique imaging filter on the Canada-France-Hawaii Telescope (CFHT) in the PIGS project to effectively pre-select candidate stars. They were confirmed by spectroscopic observations made with the Anglo-Australian Telescope (AAT), which produced the most comprehensive collection of observations ever made of pristine inner Galaxy stars.
In order to learn how these ancient stars move through the Milky Way, the PIGS observations and Gaia data were combined. It turns out that the motions of older stars become more chaotic, but even the very oldest ones found still exhibit a moderate rotation around the Galaxy’s center. They also show that a lot of these stars spend almost all of their lives in the inner Galaxy, a sphere that only reaches halfway between the Sun and the center of the galaxy.
“It is exciting to think that we are seeing stars that formed in the early phases of the Milky Way, which were previously largely out of reach,” Arentsen says. These stars are relics from the early universe because they formed less than a billion years after the Big Bang.
The accessible information in these old articles is developing quickly. In the coming years, I can’t wait to see what we learn about these first stars in our galaxy!
Provided by Royal Astronomical Society
