Researchers have discovered an exostar S0-6 near the supermassive black hole at the center of the Milky Way. The star's unique composition and 10-billion-year journey from a now-engulfed small galaxy challenge our understanding of the number and formation of stars at the center of the Milky Way.

A new study reveals that star S0-6, located near the black hole at the center of the Milky Way, originated in an outer galaxy, reshaping our understanding of stellar migration and formation in the Milky Way. A star near the supermassive black hole at the center of the Milky Way originated outside the Milky Way. This is the first time an extragalactic star has been discovered near a supermassive black hole.

Many stars have been observed near the supermassive black hole known as Sagittarius A* at the center of the Milky Way. However, the strong gravity of the black hole makes the surrounding environment too harsh for stars to form near the black hole. All observed stars must have formed elsewhere and then migrated toward the black hole. This raises the question: Where do stars form?

The central region of the Milky Way as captured by the Subaru Telescope. The image shows many stars in a field of view about 0.4 light-years across. The subject star of this study, S0-6 (blue circle), is about 0.04 light-years away from the supermassive black hole Sagittarius A* (SgrA*, green circle). Source: Miyagi University of Education/NAOJ

Research by an international team of researchers led by Shogo Nishiyama of Miyagi University of Education suggests that some of these stars may come from further away than previously thought, entirely outside our solar system. The research team used the Subaru Telescope to observe the star S0-6, which is only 0.04 light-years away from Sagittarius A*, for eight years. They determined that S0-6 is about 10 billion years old and has a chemical composition similar to stars in small galaxies outside the Milky Way, such as the Small Magellanic Cloud and the Sagittarius dwarf galaxy.

The most likely theory to explain S0-6's composition is that it was born in a now-extinct small galaxy orbiting the Milky Way and was absorbed by the Milky Way. This is the first observational evidence that some stars near Sagittarius A* formed outside the Milky Way. During its 10 billion year life cycle, S0-6 must travel more than 50,000 light-years from outside the Milky Way to reach the vicinity of Sagittarius A*. S0-6 almost certainly traveled much more than 50,000 light-years, spiraling slowly down to the center of the Milky Way rather than flying in a straight line.

Nishiyama believes there are still many questions: "Did S0-6 really originate outside the Milky Way? Does it have companions, or does it travel alone? We hope that through further investigation, we can uncover the mystery of stars near supermassive black holes."

Compiled source: ScitechDaily