Article Posted on : - Dec 14, 2009

NEW DELHI (BNS): Black holes are much closer to Earth than previously thought, according to an international team of astronomers who have for the first time measured the distance accurately.

Without using any mathematical models the astronomers came up with a distance of 7800 light years slightly more than half the distance that was previously assumed, a report by Science Daily said.

They achieved this breakthrough by measuring the radio emissions from the black hole and its associated dying star V404 Cygni, in the Cygnus constellation.

The researchers believe the previous overestimation of this distance was due to an underestimation of the absorption and diffraction of interstellar dust that can give an error margin of about 50 percent. The error margin of the new measurement is less than 6 percent.

Peter Jonker from SRON Netherlands Institute for Space Research and his colleagues applied the so-called trigonometric parallax method to a relatively near black hole - V404 Cygni. The team could accurately measure the parallax shift of the binary system using a combination of telescopes spread throughout the world, the High Sensitivity Array.

From their measurements the researchers could work out that the black hole developed from a supernova explosion, and that it moves through space at a rate of about 40 km per second. The binary-star system acquired this velocity during the explosion.

“With this information we have gained a better idea about how back holes evolve. For example, we hope to be able to answer the question as to whether there is a difference between black holes that evolve directly from the collapse of a star without a supernova and black holes that evolve via a supernova and a temporary intermediate star, a proto-neutron star. We expect that the black holes in the last group can get a kick. Black holes formed in this way could then move through space faster,” the journal quoted Jonker as saying.