First Ever Age Map of the Milky Way Galaxy Reveals History of the System
Astronomers have created the first ever chronographic map, or age map, of the halo of the Milky Way galaxy. The halo, along with the disk and bulge, are the primary components of the galaxy, which means this map may tell scientists a bit more about the evolution of our universe.
In this latest effort, the researchers used a sample of 4,700 blue horizontal-branch (BHB) stars from the Sloan Digital Sky Survey. The scientists showed that the oldest stars are concentrated in the central region of the galaxy, confirming predictions from numerical simulations of galaxy assembly.
"The oldest stars in the galaxy are concentrated toward the center of the galaxy, as predicted by previous numerical simulations of the assembly of our Milky Way," said Timothy Beers, one of the researchers, in a news release. "Surprisingly, the region of the oldest stars extends all the way to the halo region close to the sun. This Ancient Chronographic Sphere can now be explored in order to study the properties of these old stars, which will tell us about the chemistry of the early universe."
The researchers also found out the ages of dwarf galaxies and their stellar debris, which was stripped from them due to their gravitational interaction with the Milky Way.
"This information can be used to tell us the assembly history of our galaxy," said Beers. "We can now search for additional debris streams in the halo of the galaxy, based on their contrast in age, rather than simply their density contrast."
The findings reveal a bit more about the galaxy and its evolution. This, in turn, may tell researchers a bit more about the universe in general.
The findings are published in The Astrophysical Journal.
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