Brown dwarfs may provide answer to cosmic riddle


BROWN dwarfs, the recently discovered objects which lurk midway between a planet and a star, could be scattered in large, numbers throughout the universe according to new research. The finding may help to explain ones of the great mysteries of the universe, the nature of the unseen, "dark matter" which, in theory, must fill the entire cosmos.

Several brown dwarfs have been found within 150 light years of the sun, our back yard by astronomical standards. Unlike dwarfs spotted orbiting in other solar systems in clusters, these are alone in space.

Brown dwarfs are thought to, fill the gaps between the largest planets and smallest stars. They are too cool to set off the nuclear reactions which cause normal stars to shine and are therefore very faint and hard to find.

Scientists think that they could account for at least some of the unexplained "dark matter", known from measurements of gravitational influences to make up much of the universe.

The discovery of a number of new brown dwarfs will be presented this week at the National Astronomy Meeting in Liverpool. Dr Hugh Jones, from the John Moores University in Liverpool and Dr Mike Hawkins, from the Royal Observatory, Edinburgh, found four cool and faint brown dwarfs during an investigation conducted with astronomers in, France.

Using special equipment, they examined photographs taken with a telescope in Australia to search for the objects. It was only when more than loo photographic images were added, together by computer that the taint objects were noticed.

In another search, the same, technique was used to find a fifth brown dwarf, 296A which appears to be 60 times more massive than the planet Jupiter. The object, which is about loo light years away from Earth, has a luminosity 1,000th of that emitted" by the sun.

A spokesman for the Royal Astronomical Society comments "Astronomers are still arguing about how much matter is really out there, as the true amount has important consequences for the theory of galaxy formation in the early universe."