Star at the center of the Milky Way was born outside the galaxy

The study of powerful gravitational forces known as tidal forces, which are associated with the supermassive black hole Sagittarius A* at the center of our Milky Way galaxy, proves that they directly influence the formation of stars near it. But if this is really the case, then how did the stars end up in the center of the galaxy? Most likely, they first formed far from it, but subsequently migrated to their current positions.

The black hole, known as Sagittarius A*, is at the center of our Milky Way galaxy. Image:

A study conducted by an international team led by Shogo Nishiyama from Miyagi University of Education indicates that one such star, located near the supermassive black hole in the center of the galaxy, originated far beyond its boundaries. This is the first detection of a star that originated outside our galaxy and is located near a supermassive black hole. 

Using the Subaru telescope for eight years, the team observed the star S0-6. It is located 0.3 arcseconds from Sagittarius A*. The results indicate that S0-6 is more than 10 billion years old, and its chemical composition is similar to the stars of smaller galaxies outside the Milky Way, such as the Small Magellanic Cloud and the dwarf spheroidal Sagittarius galaxy. 

The central region of the Milky Way galaxy, captured by the Subaru telescope. The star S0-6 is the subject of the study, located about 0.3 arcseconds from the supermassive black hole Sagittarius A*. Image credit: NAOJ

The theory explaining the composition of S0-6 indicated that this star first originated in a small neighboring galaxy that had long been absorbed by the Milky Way. This is the first concrete evidence that some stars located close to Sagittarius A* formed outside our Galaxy. During its 10 billion-year life, S0-6 probably traveled more than 50,000 light-years to get close to a black hole. It probably took a circuitous route, gradually approaching the center in a spiral.

Shogo Nishiyama from Miyagi University of Education noted: “Did S0–6 really originate outside the Milky Way galaxy? Does it have any companions, or did it travel alone? With further investigation, we hope to unravel the mysteries of stars near the supermassive black hole.”

According to

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