The Incredible Journey of a Mysterious Star to the Center of the Milky Way

The discovery of an extragalactic star, S0-6, in close proximity to the Milky Way’s central supermassive black hole has caused scientists to question the previous understanding of the galactic center’s star population and their formation. The star's unique composition and 10 billion-year journey from a small, extinct galaxy make it an intriguing subject of study. The credit for this discovery goes to SciTechDaily.com.

A recent study uncovers the fact that the star S0-6, located near the central black hole of the Milky Way, didn't originate in our galaxy. Instead, it came from an extragalactic location, altering our understanding of star migration and the formation in our galaxy.

According to a new study, a star located near the supermassive black hole at the center of the Milky Way Galaxy has its origins outside our galaxy. This heralds the first time that a star of extragalactic origin has been found in the vicinity of a supermassive black hole.

Numerous stars are seen in proximity to the supermassive black hole known as Sagittarius A*, which is situated at the center of our galaxy. However, the intense gravity around the black hole creates an inhabitable environment for the stars to form nearby. Hence, all observed stars must have originated at a distance and later migrated towards the black hole, a fact that raises questions about their place of formation.

An illustration of the Milky Way galaxy's central region is provided by the Subaru Telescope. The representation depicts several stars within a 0.4 light-years view. The star S0-6 under study (marked with a blue circle) is just 0.04 light-years away from Sagittarius A* (indicated by a green circle). Miyagi University of Education/NAOJ holds the credit for this illustration.

An international research group led by Shogo Nishiyama from Miyagi University of Education has presented a theory that some stars might have originated from areas further than previously assumed, possibly outside the Milky Way. The team utilized the Subaru Telescope over eight years to study the star S0-6, close to Sagittarius A*. Their findings suggest that S0-6 is approximately 10 billion years old and its chemical composition resembles stars found in small galaxies outside the Milky Way like the Small Magellanic Cloud and the Sagittarius dwarf galaxy.

The theory is that S0-6 was born in a now-absorbed small galaxy that once orbited the Milky Way. This is the first piece of observational evidence indicating that some stars near Sagittaius A* might not have formed within our galaxy. Over its 10 billion year lifespan, S0-6 is believed to have journeyed over 50,000 light-years from outside the Milky Way to its current location near Sagittarius A*. It's likely that S0-6 covered more than 50,000 light-years in a spiral journey to the center as opposed to a direct path.

Several questions remain unanswered, according to Nishiyama, such as "Did S0-6 truly originate outside the Milky Way galaxy? Did it make its journey with any companions, or was it alone? With more research, we hope to answer the mysteries of stars near the supermassive black hole.”

The team's findings were published in an article titled “Origin of an orbiting star around the galactic supermassive black hole” by Shogo Nishiyama, Tomohiro Kara, Brian Thorsbro, Hiromi Saida, Yohsuke Takamori, Masaaki Takahashi, Takayuki Ohgami, Kohei Ichikawa and Rainer Schödel in the December 1st, 2023 edition of the Proceedings of the Japan Academy, Series B.