Recent research has revealed that the Milky Way's thin disk, which contains most of the stars we can see from Earth, is billions of years older than previously believed. Here are the key findings:
Using data from ESA's Gaia mission and the Large Sky Area Multi-Object Fiber Spectroscopic Telescope (LAMOST) in China, astronomers studied the ages of about 250,000 stars in the Milky Way.
This is about 2 billion years earlier than the previously estimated age of 8 to 10 billion years for the start of thin disk formation.
Implications for Galaxy Formation The discovery suggests the Milky Way formed in two discrete phases: Star formation began in the thick disk around 0.8 billion years after the Big Bang.
About 2 billion years later, a dwarf galaxy called the Gaia Sausage collided with the young Milky Way, accelerating star formation in the thick disk and kicking off the formation of the thin disk.
The age differences between stars in the thin and thick disks provide evidence for this two-phase formation scenario.
This finding could rewrite the history of our galaxy and provides new insights into when and how the Milky Way formed.