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Thursday, 5 April, 2001, 10:49 GMT 11:49 UK
New planets and 'planetars' swarm in space

The total number of planets orbiting nearby stars is now 63
By BBC News Online science editor Dr David Whitehouse

An international team of astronomers have announced the discovery of 11 new planets orbiting nearby stars.

It brings the total number of known so-called exoplanets to 63, all discovered since 1992.

One of the new planets orbits a Sun-like star at about the same distance as the Earth orbits the Sun.

Although that planet is a large gas giant, similar to our own planet Jupiter, scientists speculate that it might have rocky moons that might have the right conditions for liquid water and possibly life.

Habitable zone

Free-floating planets were found in the Orion gas cloud
The observations that detected the planets were made at the European Southern Observatory's (Eso) La Silla complex in Chile.

Light from the stars under investigation was split by a spectrometer into its component colours. This was then examined for indications that the stars were being tugged slightly by planetary companions.

One of the planets was the second one found in a three-star system. In this group, two stars are in a close orbit with a third star orbiting the pair. Astronomers say that from the new planet's viewpoint, there would be times when it had three suns in its sky.

Another planet, about the mass of Jupiter, was found in an Earth-like orbit around a star that is almost identical to our Sun.

Its orbit would be in the so-called "habitable zone" where the conditions would be right for the presence of liquid water, an essential ingredient for life. Although the Jupiter class planet would have no solid surface, any rocky moons it may have may possibly have oceans.


At the same time, a team of British astronomers have revealed new evidence to support their controversial discovery of a group of "free-floating" planets in a distant gas cloud.

Philip Lucas of the University of Hertfordshire and Patrick Roche of Oxford University said that new observations of the Orion Nebula had confirmed their existence.

Lucas and Roche first announced a year ago that they had spotted 13 new objects in infrared images of the nebula, taken by a new camera at the United Kingdom Infrared Telescope (Ukirt) in Hawaii.

They called these objects "free-floating planets" since they were smaller than 13 times the mass of Jupiter, the widely accepted limit for true planets.

"It's exciting to find these planet-sized objects floating around in space," said Lucas. "Our new results provide the first steps in the exploration of their physical properties."

The astronomers have suggested that a new name be coined for the objects they have seen: "planetars." A more sober name was recently suggested by the naming committee of the International Astronomical Union: "sub-brown dwarfs."

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