Hunting for planets in stardust

Hunting for planets Computer model image showing the distribution of comets in this system and pinpointing the location of a Neptune-like planet (represented on both images by the square; arrow shows its likely orbit)

Dr Mark Wyatt, Dr Wayne Holland, Dr Bill Dent, Dr Adrian Russell, Dr John Davies, Ms Eleanor Gilchrist, Professor Ian Robson and Mr Colin Cunningham.
UK Astronomy Technology Centre, Edinburgh.

Dr Jane Greaves.
University of St Andrews.

Mr Dan Hillier.
Royal Observatory Edinburgh Visitor Centre.

Dr Douglas Pierce-Price.
Joint Astronomy Centre, Hawaii.

Are there planets similar to our own orbiting other suns? Astronomers have so far identified over 100 systems that have 'extra solar' planets, but all are supermassive Jupiter-like bodies orbiting very close to their 'sun'. This is quite unlike our own Solar System! Now the UK Astronomy Technology Centre (UK ATC) has the first compelling evidence that planetary systems similar to our own do exist around nearby stars.

This exciting finding comes from studying the cold dust disks that surround these stars. Using the world's most powerful submillimetre-wavelength camera, SCUBA, developed at the UK ATC, astronomers have taken pictures of these disks, revealing some surprising structures and offering a unique insight into the nature of other planetary systems in our Galaxy.

The submillimetre waveband lies between the better-known infrared and radio bands of the electromagnetic spectrum and is most sensitive to very cold gas and dust. This sort of cold material is found in both the nearest stars and the most distant galaxies known to astronomy. One of the most important discoveries of the last two decades was that many nearby stars are surrounded by cold dust disks that come from a reservoir of comets orbiting further from their stars than Neptune is from the Sun.

'If you want to understand the origins of these fundamental astronomical structures, the submillimetre is the waveband of choice', says Mark Wyatt of the UK ATC team. 'The SCUBA camera was installed on the James Clerk Maxwell Telescope in Hawai'i in 1997 and opened up this exciting field of astronomy for the first time. Suddenly we had the capability to take pictures of these dust disks.'

The SCUBA observations show that the dust lies in vast disks around the stars, but is surprisingly concentrated in just a few 'clumps'.

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