(ORDO NEWS) — Using data collected by the European Space Agency’s (ESA) Gaia mission, astronomers have shown that a portion of the Milky Way known as the “thick disk” formed 13 billion years ago, about 2 billion years earlier than than expected, and only 0.8 billion years after the Big Bang.
These amazing results were obtained by a team led by Maosheng Xiang of the Max Planck Institute for Astronomy, Germany, who analyzed data collected by the Gaia space mission and the Large Sky Area Multi-Object Fiber Spectroscopic Telescope (LAMOST) ground-based observatory, China. Scientists have been able to accurately determine the age of 250,000 subgiant stars, which in turn
Our Galaxy consists of several structural elements. The most ancient structure is a spherical halo surrounding the galactic disk, which is a younger formation. The disk consists of two components, thick and thin disks.
The thin disk contains most of the stars observed from Earth and looks like a hazy light band in the sky when looking at the Milky Way. The thick disk is almost twice as thick as the thin disk, but has a smaller diameter and contains only a few percent of the Milky Way’s stars.
The data obtained as a result of this analysis surprised scientists. It turned out that the formation of the Milky Way proceeded in two stages.
The first stage, which began just 0.8 billion years after the Big Bang, formed the stars of the Milky Way’s thick disk and the inner regions of the halo.
This process accelerated dramatically about 2 billion years later, when the dwarf galaxy Gaia Enceladus crashed into the Milky Way. The thin disk, which includes our solar system, appeared only at the subsequent, second stage of the formation of the Galaxy, the authors explained.
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