2023-07-10 22:13:00
12 billion years
11 July 2023 00:13 Robert Klatt
Old stars in the inner region of the Milky Way )0.4 YB CC – egdirbmaC ,ymonortsA fo etutitsnI ,nestnerA eknA dna htimS .J adnamA :noisserpmi s’tsitra ,aiaG/ASE(Photo: ©
Old stars allow us to look back to the early days of the universe. Astronomers have now compiled the most comprehensive collection of old stars from the center of the Milky Way and made surprising observations in the process.
Cardiff (Wales). Some stars that formed in the first billion years after the Big Bang still exist today. They allow astronomy to study what galaxies looked like when they were just beginning to form. They are recognized by their chemical composition, which consists mainly of hydrogen and helium and has significantly fewer heavy elements than younger stars like the sun. They are primarily sought in the low density of the halo around our galaxy because they are easier to find there.
However, models of galaxy formation show that the very oldest stars should be found in the dense inner regions of the Milky Way. However, their detection in this region is difficult because the view of the center of the galaxy is blocked by large amounts of interstellar dust and old stars are extremely rare compared to the majority of young stars there.
Map of the oldest stars in the Milky Way
Researchers from the Pristine Inner Galaxy Survey (PIGS) team led by Dr. Anke Arentsen from the University of Cambridge, according to the Royal Astronomical Society (RAS) presented a comprehensive map of the oldest stars at the center of the Milky Way at the University of Cardiff’s 2023 National Astronomy Meeting. The discovered stars rotate slowly around the center of the galaxy, although they were thought to have formed in a chaotic manner. They also appear to spend most of their long lifespans near the galactic center.
Image filter am Canada-France-Hawaii-Telescope
The old stars were discovered thanks to a special image filter on the Canada France Hawaii Telescope (CFHT), which makes it possible to efficiently preselect candidate stars. Subsequently, the identity of the stars was confirmed by spectroscopic observations at the Anglo-Australian Telescope (AAT). The researchers working with Arentsen were thus able to carry out the most extensive collection of detailed observations of stars in the original inner region of the galaxy to date.
“It’s exciting to think that we’re seeing stars formed in the earliest stages of the Milky Way, which were previously largely unreachable. These stars were likely formed less than a billion years after the Big Bang, making them relics from the early Universe. The data available for these ancient objects is growing rapidly. I’m excited to see what we will learn about these first stars to populate our galaxy over the next few years.”
Gaia space mission reveals motion of stars
The PIGS observations were then combined with data from the Gaia space mission to study how these ancient stars move through the Milky Way. It turned out that the older the stars are, the more chaotic their movements are, but even the very oldest stars still show an average rotation around the center of the galaxy. They also show that many of these stars spend most of their lives in the inner reaches of the galaxy, in a sphere only halfway between the galactic center and the Sun.
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