Martin Ward, Professor of Astronomy at the University of Leicester, will announce today at NASA the discovery of a new type of black hole. He is part of an international team who made the discovery using the X-ray space telescope 'Chandra'.
Until now, scientists have observed only two types of black holes - ones that are about the same mass as stars, and ones that are a million or a billion times bigger than the mass of a star.
Using Chandra the team of scientists have probed deep into the galaxy called M82. The X-ray pictures reveal a level of detail previously hidden to astronomers. Most amazing is the giant binary system - that is two stars orbiting around each other - deep inside the galaxy. The larger of the two stars is around 500 times as big as our Sun. 'This is really some binary' says Martin Ward 'We had previously thought that the biggest binary would be only a fraction of this size - this is an enormously powerful X-ray source and the only explanation is that it must be a black hole.'
Ward goes on to explain 'Finding this 'middle sized' black hole is like finding the missing bit of a puzzle. We already knew that black holes a few times the mass of the Sun existed, and that there are really huge black holes at the centres of galaxies - but this new type of black hole fits neatly in between the two.'
The next puzzle is to discover how this middle-sized black hole formed, away from the ideal environment of the strong gravity pull present at the centre of a galaxy. Scientists speculate that it could be a ‘cannibal' that has eaten lots of other stars to grow to its present mass.
The discovery means that astronomers will have to re-think some of their ideas about how stars form and the role of black holes in the cosmic scheme.
An ISDN studio quality radio interview facility is available at the University of Leicester.
Delores Beasley, NASA Headquarters, Washington DC Tel: 00 1 202 358 1753
Webcast: 1 pm EDT (5 pm BST) at: http://www.nasa.gov/ntv/ntvweb.html
Broadcast: NASA TV on satellite GE-2, transponder 9C at 85 degrees West longitude, vertical polarization, frequency 3880 MHz. Audio of 6.8 MHz
Images: http://chandra.harvard.edu/ and http://www.nasa.gov
The other scientists in the international team are from the USA (Harvard and MIT) and Japan.
Chandra's ability to see through the veil of dust shows for the first time that the X-rays from galaxy M 82 come from a host of separate individual sources, each of which generates its own X-rays. The researchers found that one x-ray source has increased its brightness by nearly 10 times, and in addition its X-rays flicker up and down about every 10 minutes. Together these bits of information point strongly to the X-rays coming from a binary system.
The reason why the Chandra satellite was needed to make this discovery is because its superb fine detailed images could separate one X-ray source from another. Imagine a Christmas tree with dozens of randomly flashing lights on it. When viewed close up we can see each separate light flashing on and off. But now imagine looking at it from far away (or equivalently with blurred vision), now the lights all merge together, and the brightness changes just average out give to a constant intensity.
The special camera used to obtain the X-ray images that led to the discovery described above, is called the High Resolution Camera (HRC). It was built for NASA by the Harvard Smithsonian Center for Astrophysics. The UK had a significant involvement in the development and calibration of the detectors used in the HRC, they are called MCP (micro-channel plates). The UK effort was led by George Fraser of Leicester University, and was funded by PPARC.
Professor Martin Ward is funded by the Particle Physics and Astronomy Research Council.
The Particle Physics and Astronomy Research Council (PPARC) is the UK's strategic science investment agency. It funds research, education and public understanding in four broad areas of science - particle physics, astronomy, cosmology and space science.
PPARC is government funded and provides research grants and studentships to scientists in British universities, gives researchers access to world-class facilities and funds the UK membership of international bodies such as the European Laboratory for Particle Physics, CERN, and the European Space Agency. It also contributes money for the UK telescopes overseas on La Palma, Hawaii, Australia and in Chile, the UK Astronomy Technology Centre at the Royal Observatory, Edinburgh and the MERLIN/VLBI National Facility.
PPARC's Public Understanding of Science and Technology Awards Scheme provides funding to both small local projects and national initiatives aimed at improving public understanding of its areas of science.
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