05/12/2011

Black holes can be attributed to one of the most amazing and bizarre predictions of Einsteinâ€™s theory of gravity. The size of the black hole are taken as a starting point, but surrounding this point of an imaginary surface of finite size (the event horizon), and all that gets there, it is forever lost to the rest of the universe.

Contrary to its reputation relentless devourer of matter and energy, the regions around black holes themselves are often sources of powerful radiation. For example, if it is surrounded by material in the form of a disk, the admission of gas from the surrounding objects, it interacts with the disk, which leads to emission of radiation and matter.

Black hole is simple enough that it can be described by three parameters only: mass momentum (quantity rotational movement), and an electric charge. But with the measurement values of these things are already not so easy. The charge is usually taken as negligibly values, which leaves only two options. The mass can be found if a black hole is orbiting companion, as a recurrent orbital motion is strictly based on their mass and size of the orbit. And in order to calculate the size of the orbit is required to know the exact distance to it.

All these difficulties have been overcome in the course of the three studies that have been published in the last month. Thanks to this new approach, they were able to calculate the distance to an accuracy of about 6% to the black hole Cygnus X-1: it is located at a distance of 6060 light years from Earth. By calculating the distance, the scientists were able to deduce the mass of the black hole: 14.8 solar masses, with about the same accuracy as 7%. The remaining parameter, the momentum of rotation, can now also be calculated. According to calculations the team, this black hole is rotating at a speed of 95% of the possible maximum of Einsteinâ€™s theory, so its event horizon makes about 800 revolutions per second. These fascinating objects are no less mysterious and, nevertheless, obtained in these studies results marked a significant advancement in our understanding of their basic properties.

Original: Physorg