New planet's trail could signal life in space
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news.scotsman.com]
ALASTAIR DALTON SCIENCE CORRESPONDENT
ASTRONOMERS said there was an "odds-on" chance of intelligent life in space after new observations produced the best evidence yet of planets circling stars outside our solar system.
A team led by the UK Astronomy Technology Centre (ATC) in Edinburgh announced yesterday that they had found the dusty wake of a Saturn-like planet around one of the brightest stars in the sky.
The discovery of a huge, distorted disc of cold dust around Fomalhaut, 25 light years away, follows indirect observations of 100 other planets outside the solar system. They had been detected by the way their gravitational forces causes their stars to "wobble".
The dust distortion around Fomalhaut is thought to be caused by the gravitational influence of a planet a large distance from the star, which is tugging on the disc.
Significantly, the planet is much further away from Fomalhaut than previously discovered extra-solar planets, which have much closer orbits of their stars.
The Edinburgh-built instrument which detected it will now survey more than 100 other nearby stars.
Dr Wayne Holland, who led the team, which is based at the Royal Observatory of Edinburgh, said the discovery provided the strongest evidence so far that other solar systems existed.
He said: "If that is the case, then why shouldn’t there be planetary systems like our own that contain Earth-like planets?
"Personally speaking, I think it must be odds-on that there is intelligent life elsewhere in the universe, and I think one day we will find it - or they will find us."
Fomalhaut is some 2.3 times larger than the sun, and is the 17th brightest star in the sky. It lies in the constellation of Piscis Austrinus, or the southern fish, and takes its name from the Arabic for fish’s mouth.
Dr Holland said: "We were amazed to find that the disc is actually bent about the star.
"This strongly suggests there is an orbiting giant planet shaping the dust we see."
However, he said there was little chance of finding life on the planet because it was under constant bombardment from a surrounding belt of comets.
The planetary system around Fomalhaut is thought to resemble our solar system in its relative infancy, at 200 million years old. By contrast, the sun is 4.5 billion years old.
A specially-cooled camera called SCUBA was used to detect the dust because it is too cold and emitted insufficient light to be visible to optical telescopes such as the Hubble Space Telescope.
SCUBA operates in the "submillimetre" region of the electromagnetic spectrum, which lies between infrared light and radio waves. Its detectors are cooled to just 0.1C above absolute zero, -273C.
The camera was attached to the James Clerk Maxwell Telescope in Hawaii, which is the world’s largest for studying light at such wavelengths.
Fomalhaut was targeted because excess heat emissions were found to be coming from it in a study 20 years ago.
Professor Ian Robson, the ATC’s deputy director, said a planned more powerful camera, SCUBA 2, would be able to assess discs like the one round Fomalhaut much more quickly.
He said: "It will revolutionise our search for evidence of planetary systems."
Dr Jane Greaves, a fellow member of the team, said: "Our previous image did not have the resolution to pinpoint the detail we are now seeing.
"We could see a hole in the disc near the star, and thought it was cleared out by the gravitational pull of a planet like Jupiter, but we had no idea there was anything further from the star."
Dr Mark Wyatt, another team member, said the dust showed evidence of comet activity.
He said: "Our models of the Fomalhaut disc suggest that a planet similar in mass to Saturn is creating a wake or trail of dust. The gravity of the planet creates points near its orbit called ‘resonances’, where comets get trapped. When two comets collide, they release a shower of dust that we see as a bright spot in the disc."