The 18,000 oldest stars in the Milky Way are located in the constellation Sagittarius, from the Milky Way’s protogalaxies (primitive bodies of gas and dust) from which the first stars in the young Milky Way formed 12.5 billion years ago. The researchers found that the mass of this group of ancient stars is about 0.2% of the total mass of the Milky Way.
To discover this “ancient heart”, astronomers used data provided by the European Space Agency’s (ESA) “Gaia” probe. Launched in 2013, Gaia weighs 1,630 kilograms to create the most detailed and accurate map of the Milky Way.
The journey to find the “ancient heart” of the Milky Way begins with a search of the most crowded region within the Milky Way for a very small number of stars “at the same age” as the Milky Way, some 13 billion years ago. To find this small group of stars, the researchers analyzed data collected by Gaia for 2 million stars, located within 30 degrees of the center of the Milky Way, with lower masses, longer lifetimes, and lower metallicities. Ultimately, they mapped out the “ancient heart” on which the Milky Way grew.
The discovery of the Milky Way’s “ancient heart” revealed two things, the researchers say: First, stars in protogalaxies revolve much less around the center of the galaxy than young stars; The merger, but the stars at the center of the Milky Way were not affected.
The researchers hope that by further analyzing this part of the “ancient heart”, it will reveal more information related to the Milky Way, such as supernovae. These supernovae had to explode during their formation to produce the ratios of early chemical elements that people see today.
“It has long been thought (based on theory and simulations) that the oldest stars in the Milky Way are located in The very centers of galaxies, and our findings show that they are numerous.”
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