Two astrophysicists at NASA’s Goddard Space Flight Center in Greenbelt, Md., Nikolai Shaposhnikov and Lev Titarchuk, have successfully tested a new method for determining the masses of black holes.
This elegant technique, which Titarchuk first suggested in 1998, shows that the black hole in a binary system known as Cygnus X-1 contains 8.7 times the mass of our sun, with a margin of error of only 0.8 solar mass.
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