Dark matter affects the rotation of the galaxy and the stars located at its outer edges, and this was primarily the reason why scientists believed that dark matter exists.
A research team from the British University College London (UCL) was able to observantly confirm a 3-decade-old hypothesis that the center of our galaxy, the Milky Way, is slowing down with time, which could help to achieve a better understanding of the nature of dark matter, one of the biggest mysteries of the universe.
Gaia is a European Space Agency (ESA) space observatory that aims to compile an accurate 3D informational list of about a billion stars in our galaxy, less than 1% of their stars.
According to the study, researchers from this team focused mainly on the so-called Hercules stream, which is a mass of stars located far from the center of the galaxy, but nonetheless rotates affected by its gravity, compared to neighboring regions.
Then the team used a famous physical relationship called orbital resonance, which states in one of its precise forms that as the galactic center slows down in its rotation, the stars of the Hercules Stream will move back as they rotate around the galactic center.
The secret of the current Hercules
By examining the stars in the Hercules stream, it was found that they bear a different chemical signature, that they are 10 times richer in heavy elements compared to their neighbors, and this proves that they were once close to the center of the galaxy and then moved away from it because only the stars close to the center can contain this high concentration from heavy elements.
Using this data, the team concluded that the galactic center stream, which takes the form of a massive bar made up of billions of stars, has slowed its rotation by at least 24 percent since it first formed about 11-13 billion years ago.
According to the study, these interesting results support the theory that there is so-called “dark matter”, a substance that we do not know anything about yet, and researchers in this area imagine that it envelops galaxies as an apricot envelops its seed.
Because of this, dark matter affects the rotation of the galaxy and the stars located in its outer edges, and that was mainly the reason why scientists believed the existence of dark matter, but unfortunately we do not know more about it than that.
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