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An ancient extragalactic star has been discovered in the center of the Milky Way

A recent study by Japanese astronomers from the Miyagi Educational University revealed the presence of an unusual star designated S0-6, situated near a supermassive black hole in the center of the Milky Way. This star materializes to have emerged from a smaller galaxy that was once swallowed up by ours.

The supermassive black hole Sagittarius A* is located in the center of our Galaxy. It attracted the attention of astronomers because of the substantial number of stars observed nearby. However, we apprehend that star formation in such conditions is hindered by the extremely powerful tidal forces created by these massive objects that can disrupt the star formation process.

Therefore, all the stars observed near Sagittarius A* should have formed elsewhere, then migrated to the central part of the Galaxy, often associated with complex gravitational interactions. Recent observations by an international contingent led by Shogo Nishiyama from Miyagi Educational University propose that some stars may even have an extragalactic origin.

As part of this work, academicians have been employing the Subaru telescope for eight years to closely examine the star S0-6, situated just 0.3 arcseconds from Sagittarius A*. Observations have exhibited that S0-6 is over 10 billion years old, and its chemical composition is akin to that of stars found in small galaxies outside the Milky Way. Thus, the composition of S0-6 intimates that it probably originated in a small, now-extinct galaxy that orbited the Milky Way and was subsequently absorbed. This observation represents the first physical evidence that some stars near Sagittarius A* could have formed exterior to our galaxy.

During a lifetime of 10 billion years, S0-6 had to travel an immense distance to reach its current position near Sagittarius A*. However, the academicians note that it is highly likely that the real path of S0-6 was much longer than 50,000 light-years, and that it pursued not a straight line, but a descending spiral trajectory towards the center.

This new revelation also raises a number of questions: did S0-6 really come from outside the Milky Way? Does she have companions, or is she traveling alone? In the course of further inquiry, scientists hope to unravel the mysteries surrounding stars in the vicinity of a supermassive black hole.

As next-gen telescopes augment our competency to survey and analyze the chemical compositions of stars in the galactic core, more rogue stars akin to S0-6 that migrated from other galaxies could potentially be discovered and characterized. Tracing back their trajectories and origins could reveal critical clues about past gravitational interactions between the Milky Way and its satellite dwarf galaxies. Unlocking these stellar narratives will ultimately assist map out the formation and merger history of our home galaxy across cosmic timescales.

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