Credit: NASA/JPL-Caltech/R. Hurt (SSC/Caltech)
Key points:
- Three stars at the heart of the Milky Way have been determined to be much younger than previously thought.
- That section of the galaxy was thought to be ancient, but the discovery shows there is active star formation occurring.
- The study sheds significant light on our understanding of the early universe.
Data from a ten-meter telescope in Hawaii has revealed surprising information about three stars at the very heart of the Milky Way—they are unusually young and have a puzzling chemical composition.
The study, which has been published in The Astrophysical Journal Letters, examined a group of stars located in the nuclear star cluster that makes up the heart of the galaxy. The nuclear star cluster has mainly been seen as a very ancient part of the galaxy. But the researchers’ new discovery of such young stars indicates that there is also active star formation going on in this component of the Milky Way.
The researchers used high-resolution data from the Keck II telescope in Hawaii, one of the world’s largest telescopes with a mirror ten meters in diameter. They measured how much iron the stars contained, as young stars have more of heavy elements since they are formed to an increasing extent over time in the universe.
To determine the level of iron, the astronomers observed the stars’ spectra in infrared light which, compared with optical light, are parts of the light spectrum that can more easily shine through the densely dust-laden parts of the Milky Way. It was shown that the iron levels varied considerably, which surprised the researchers.
“The very wide spread of iron levels could indicate that the innermost parts of the galaxy are incredibly inhomogeneous, i.e. unmixed,” said Brian Thorsbro, researcher in astronomy at Lund University. “This is something we had not expected and not only says something about how the centre of the galaxy appears, but also how the early universe may have looked.”
The study sheds significant light on our understanding of the early universe and the functioning of the very center of the Milky Way.
“Personally, I think it is very exciting that we can now study the very center of our galaxy with such a high level of detail. These types of measurements have been standard for observations of the galactic disc where we are located, but have been an unreachable goal for more faraway and exotic parts of the galaxy. We can learn a lot about how our home galaxy was formed and developed from such studies,” said study author Rebecca Forsberg.