Kamis, April 03, 2008

Astronomers find new planets

Correspondents in Washington | April 03, 2008

ASTRONOMERS using robotic cameras say they have found 10 new planets outside our solar system, while a second team believes it has found the youngest planet yet.

The findings add to a growing list of more than 270 so-called extrasolar planets, they told a meeting of astronomers in Belfast, Northern Ireland.

The robot team is called "SuperWASP", for Wide Area Search for Planets, and the cameras look for planets transiting, or crossing in front of, their stars.

The light from the sun fades just slightly when this happens, and astronomers can extrapolate the size and location of the planet.

Most planets around other stars have been found using a different method, measuring the tiny tugs that a planet makes on its sun's gravitational field.

Don Pollaco of Queen's University in Belfast and colleagues used banks of cameras in Australia, Spain's Canary Islands, South Africa, Arizona, Hawaii, Chile and France to discover the 10 new extrasolar planets.

The planets range in mass from half the size of Jupiter to more than eight times the size of Jupiter, the largest planet in our solar system.

One orbits its sun once a day and is so close that its daytime temperature could reach about 2300°C.

Jane Greaves of the University of St Andrews in Scotland and colleagues said they found a baby planet while using radio astronomy to examine a disk of gas and rocky particles around the star HL Tau.

This star is also thought to be young -- 100,000 years old compared to our 4.6 billion-year-old Sun.
They found a clump which appears to contain rocky pebbles.

"We see a distinct orbiting ball of gas and dust, which is exactly how a very young protoplanet should look," Greaves said in a statement.

"In the future, we would expect this to condense out into a gas giant planet like a massive version of Jupiter. The protoplanet is about 14 times as massive as Jupiter and is about twice as far from HL Tau as Neptune is from our sun."

Anita Richards of Britain's Jodrell Bank observatory in Cheshire, said the finding "gives a unique view of how planets take shape".

"The new object, designated HL Tau b, is the youngest planetary object ever seen," she added.

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