Mystery of Milky Way's Young Stars Surrounds Supermassive Black Hole

Lurking at the heart of the Milky Way, Sagittarius A* (Sgr A*) is a supermassive black hole four million times the mass of the sun, surrounded by a puzzling collection of young, massive stars whose orbits have long defied explanation. Astronomers have proposed various competing theories to account for these stars, but none has been able to explain all of them together.