science

An international team of astronomers has made direct observations of clumps of gas, orbiting a black hole at ten per cent of the speed of light. This is the first time scientists have been able to see individual X-ray- emitting lumps of matter go all the way round a black hole.

By Lucy Sherriff (lucy.sherriff at theregister.co.uk)
Published Monday 10th January 2005 19:10 GMT

The data provide an insight into previously speculative area of science. For the first time, star gazers have concrete measurements of the orbital period and orbital speed of matter circling a black hole. The researchers have used the information to work out that the black hole they are studdying must be at least 300,000 times as massive as our own sun.
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Artist's impression of matter falling into a black hole

Dr Lance Miller of the University of Oxford commented: "If the black hole in question were placed in our Solar System, it would be as wide as Mercury's orbit, with the three clumps of matter detected orbiting as far out as Jupiter. They orbit the black hole in a lightning-quick 27 hours, compared to the 12 years it takes Jupiter to orbit the Sun."

Miller was part of a team of astronomers that included researchers at NASA's Goddard Space Flight Center and University of Maryland Baltimore County. The team analysed observations from the EPIC X-ray cameras on the European Space Agency's XMM-Newton satellite.

The team was able to make the observations by tracking flares on the disc of matter swirling round the black hole. The mechanism that produces the flares is still unknown, but Miller explains that tracking their movement was simple.

"We think we're viewing the accretion disk at a slightly tilted angle, and we see the light from each of these flares rise and fall in energy as they orbit the black hole. With a measured velocity and orbital period, we could determine the black hole mass using relatively simple Newtonian physics," he said. ®

http://www.theregister.co.uk/2005/01/10/seen_black_hole_matter/