Smallest black hole ever 'discovered'
Astronomers have discovered what they claim is the smallest and lightest known black hole which has amazing tidal force.
Using a new method, they have identified the black hole which has a mass only about 3.8 times greater than Sun and a diameter of only 15 mile . It resides in a Milky Way Galaxy binary system known as XTE J1650-500, the NASA said.
"This black hole is pushing the limits. For many years astronomers have wanted to know the smallest possible size of a black hole and this little guy's a big step toward answering that question," lead astronomer Nikolai Shaposhnikov of NASA's Goddard Space Flight Centre, Greenbelt, said.
According to the astronomers, smaller black holes like the one in J1650 exert stronger tidal forces than the larger black holes found in the centers of galaxies, which make the little guys more dangerous to approach.
"If you ventured too close to J1650's black hole, its gravity would tidally stretch your body into a strand of spaghetti," Shaposhnikov said.
The method used by the NASA team to identify the black hole is called QPO or quasi-periodic oscillation whose frequency depends on the black hole's mass -- as they increase in mass, the QPO clock ticks slower and slower.
In their study, they extend their result to seven other black holes, three of which have well-determined masses. "In every case, our measurement agrees with the other methods. We know our technique works because it has passed every test with flying colours," co-author Lev Titarchuk said.
When the astronomers applied their method to XTE J1650-500, they calculated a mass of 3.8 Suns, with a margin of uncertainty of only half a Sun. This value is well below the previous black hole record holder with a reliable mass measurement, GRO 1655-40, which tips the scales at 6.3 Suns.