Going gets tough for life in other Solar Systems

Though the star Tau Ceti is similar to the Sun, any planets it has are unlikely to be havens for life, say a team of UK astronomers. Using submillimetre images of the disk of material surrounding Tau Ceti, they found that it must contain more than ten times as many comets and asteroids than there are in the Solar System. With so many more space rocks hurtling around the star, devastating collisions of the sort that could lead to the destruction of life would be much more likely in the Tau Ceti system than in our own planetary system.

Publication of the result in Monthly Notices of the Royal Astronomical Society coincides with an exhibit 'Hunting for Planets in Stardust' at the Royal Society Summer Exhibition by the same science team from the UK Astronomy Technology Centre in Edinburgh and the University of St Andrews.

Tau Ceti, only 12 light years away, is the nearest Sun-like star and is easily visible without a telescope. It is the first star to be found to have a disk of dust and comets around it similar in size and shape to the disk of comets and asteroids that orbits the Sun. But the similarity ends there explains Jane Greaves, Royal Astronomical Society Norman Lockyer Fellow and lead scientist: "Tau Ceti has more than ten times the number of comets and asteroids that there are in our Solar System. We don't yet know whether there are any planets orbiting Tau Ceti, but if there are, it is likely that they will experience constant bombardment from asteroids of the kind that is believed to have wiped out the dinosaurs. It is likely that with so many large impacts life would not have the opportunity to evolve."

The discovery means that scientists are going to have to rethink where they look for civilisations outside our Solar System. Jane Greaves continues "We will have to look for stars which are even more like the Sun, in other words, ones which have only a small number of comets and asteroids. It may be that hostile systems like Tau Ceti are just as common as suitable ones like the Sun."

The reason for the larger number of comets orbiting Tau Ceti is not fully understood, explains Mark Wyatt, another member of the team: "It could be that our Sun passed relatively close to another star at some point in its history and that the close encounter stripped most of the comets and asteroids from around the Sun."

The new results are based on observations taken with the world's most sensitive submillimetre camera, SCUBA. The camera, built by the Royal Observatory, Edinburgh, is operated on the James Clerk Maxwell Telescope in Hawaii. The SCUBA image shows a disk of very cold dust (-210 ºC) in orbit around the star. The dust is produced by collisions between larger comets and asteroids that break them down into smaller and smaller pieces.

UK participation in the James Clerk Maxwell Telescope is provided by the Particle Physics and Astronomy Research Council (PPARC). Professor Ian Halliday, PPARC Chief Executive said "SCUBA continues to unveil the mysteries of planetary systems, in this case the "asteroid alley" that is Tau Ceti; - clearly a place you would not wish to be."


Images

Artist's impression of the Tau Ceti landscape

Artist's impression: For any planets orbiting Tau Ceti, the skies will be criss-crossed with comets and meteors will frequently strike the surface.
Credit: David A Hardy.

 
SCUBA image of Tau Ceti

SCUBA Image: Image of the disc of dust particles around the star Tau Ceti, taken with the submillimetre-wavelength camera SCUBA. The false colours show the brightness of the disc. Its diameter is slightly larger than the Solar System. Credit: James Clerk Maxwell Telescope.

 
James Clerk Maxwell Telescope

The James Clerk Maxwell Telescope (JCMT) was used to take the image of the Tau Ceti dust disk. It is the world's largest single-dish submillimetre telescope. It collects faint submillimetre signals with its 15 metre diameter dish. It is situated near the summit of Mauna Kea on the Big Island of Hawaii, at an altitude of approximately 4000 metres (14000 feet) above sea level.
Credit: Nik Szymanek.


Notes for Editors

The Royal Society Summer Exhibition

The Royal Society Summer Exhibition runs from 5 to 8th July and is open to the general public Monday 5th July 6pm - 9pm; Tuesday 6th July 11am - 4.30pm; Wednesday 7th and Thursday 8th July 10am - 4.30pm.

There is a media preview on Tuesday 5th July 10am - 11am. To pre-register please email press@royalsoc.ac.uk.

Observing Tau Ceti

Tau Ceti is in the constellation Cetus. Although it is visible without a telescope, at this time of year it rises in the South East at about 3am - just before the sun, so is very hard to spot.

The ROE & UK ATC

The Royal Observatory, Edinburgh comprises the UK Astronomy Technology Centre, the Institute for Astronomy (IfA) of the University of Edinburgh and the ROE Visitor Centre. The UK Astronomy Technology Centre is a scientific site belonging to the Particle Physics and Astronomy Research Council (PPARC). The mission of the UK ATC is to support the mission and strategic aims of PPARC and to help keep the UK at the forefront of world astronomy by providing a UK focus for the design, production and promotion of state of the art astronomical technology.

The James Clerk Maxwell Telescope (JCMT)

The JCMT is the world's largest single-dish submillimetre telescope. It is situated near the summit of Mauna Kea on the Big Island of Hawaii, at an altitude of approximately 4000 metres (14000 feet) above sea level. It is operated by the Joint Astronomy Centre, on behalf of the UK Particle Physics and Astronomy Research Council, the Canadian National Research Council, and the Netherlands Organisation for Scientific Research.

SCUBA

SCUBA (the Submillimetre Common-User Bolometer Array) is the world's most powerful submillimetre camera. It is attached to the James Clerk Maxwell Telescope, and contains sensitive detectors called bolometers, which are cooled to 60 milliKelvin, 0.06 degrees above absolute zero (60 milliKelvin is about -273.1 Celsius, -459.6 Fahrenheit). SCUBA was built in the UK by the Royal Observatory, Edinburgh, at what is now the UK Astronomy Technology Centre.

PPARC

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, particle astrophysics 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 Organisation for Nuclear Research, CERN, the European Southern Observatory 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.


Contacts

Dr Jane Greaves
Astronomer, University of St Andrews
jsg5@st-andrews.ac.uk
07745 127391

Julia Maddock
PPARC Press Office
Julia.maddock@pparc.ac.uk
01793 442094

Eleanor Gilchrist
ATC Press Office
efg@roe.ac.uk
0131 668 8379

Jacqueline Mitton
Press Officer, Royal Astronomical Society
jmitton@dial.pipex.com
01223 564914

Dr Douglas Pierce Price
James Clerk Maxwell Telescope
outreach@jach.hawaii.edu
+1 808 969 6524