Astronomers may have discovered an extragalactic intruder among stars that orbit the supermassive black hole at the heart of our Milky Way, Sagittarius A* or Sgr A*.
Sgr A* is surrounded by a cavalcade of stars, the rapid orbits of which have helped astronomers determine that the black hole has a mass around 4.5 million times that of the sun. Yet, as useful as these stars are, their existence is somewhat mysterious. This is because the intense gravity of Sgr A* should make the heart of the Milky Way an environment that is far too turbulent and violent to allow the formation of stars at all.
