Parts of the Milky Way Are , Older Than Previously Thought, Study Reveals.
Space.com reports that the Milky Way is often viewed as being made up of two major parts:.
The thin disk, where the solar system and much of what we know as the Milky Way resides, and the thick disk, which is larger and more sparse.
A new study, conducted by astronomers from the Max-Planck Institute for Astronomy in Heidelberg, Germany, .
Has found that the thick disk appears to be about 2 billion years older than previously thought.
It's likely that the thick disk formed just 800 million years after the Big Bang.
For the study, the team examined the Milky Way's sub-giants, which are stars existing in the stage between regular stellar life and the red giant phase.
Since a star is only ever a sub-giant for a few million years, astronomers are able to more accurately determine its age.
The ages of 250,000 sub-giants were discovered as part of the study by using data from China's Large Sky Area Multi-Object Fiber Spectroscopic Telescope (LAMOST) and the European Space Agency's (ESA) Gaia mission.
The researchers deduced that most of the Milky Way's star formation occurred in two waves.
The first wave has to do with the thick disk and took place 13 billion years ago.
Then, the Milky Way collided with another galaxy, Gaia-Sausage-Enceladus, resulting in the thin disk about 6 billion years later.
Since the discovery of the ancient merger with Gaia-Sausage-Enceladus, in 2018, astronomers have suspected that the Milky Way was already there…but we didn’t have a clear picture of what that Milky Way looked like, Maosheng Xiang, an astronomer at the Max Planck Institute for Astronomy and one of the paper's authors, via statement published by the ESA
