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A scientist using NASA 's Chandra X-ray Observatory has found evidence that two white dwarf stars are orbiting each other in a death grip , destined to merge . Overlaid are the best fitting simultaneous orbital solutions , which assume that all the stars are orbiting the same central point mass . The two stars are orbiting each other with a period of 170 years having a separation of 40 AU , about the distance of Pluto from the Sun . makes it seem as though the stars are orbiting the earth once a day . These high-speed stars are orbiting a small object 2.7 million times more massive than the Sun , evidence that strongly suggests the central object is indeed a black hole . Many stars are observed to be in binary systems , where two stars are orbiting each other ( as the Earth orbits the sun ) . This implies that the X-ray source is a binary star system where two white dwarf stars are orbiting each other ( above , illustration ) only 50,000 miles apart , making it one of the smallest known binary orbits in the Galaxy . Their findings support a previous theory that stars are orbiting the galaxy 's central black hole in a lopsided path and are piling up - like a cosmic traffic jam - at a section farthest away from the black hole . This implies that the X-ray source is a binary star system where two white dwarf stars are orbiting each other only 50,000 miles apart , making it one of the smallest known binary orbits in the Galaxy .