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New Planet Search Methods Push Tally Near 300

April 3, 2008

Astronomers have struggled for centuries to find our solar system’s planets, let alone any outside of our relatively puny cosmic neighborhood.

Yet during only the past 13 years, observers have tracked down nearly 300 distant bodies beyond our system thanks to rapid advances in ground-based telescope technology and methods.

Ten worlds
alone were identified by a group of astronomers in the past six months using
earthbound instruments, and another team of scientists just announced they have
found the youngest-ever planetary infant. The hunt for the first Earth-like
planet
, however, is still on.

Observers
discussed the state of their search for extrasolar planets, as worlds beyond
the solar system are known, during the Royal Astronomical Society’s National
Astronomy Meeting in Belfast, U.K., this week.

Sting
operation

Extrasolar
planets are tough for telescopes to detect unless the objects are about the
size of Jupiter, which is why astronomers rely on unique methods to find the
elusive bodies.

Periodic
wiggles in stellar movement can signal an orbiting world’s gravitational tug on
its star. Another method looks for dips in stellar brightness called
transits
— when planets pass directly in front of a star and block out some
of the light.

Instead of
spending weeks babysitting single stars to seek out gravitational wiggles, as
many planet-hunters do, some European astronomers are monitoring millions of
stars with inventive camera setups such as one called SuperWASP.

“SuperWASP
is now a planet-finding production line,” said Don Pollacco, a SuperWASP
project member and a Queen’s University Belfast (QUB) astronomer.

In the past
six months alone, Pollacco said, the project’s two batteries of cameras in South Africa and the Canary Islands have pinpointed 10 new planets, for which SuperWASP has also
estimated size and mass.

“[It] will
revolutionize the detection of large planets and our understanding of how they
were formed,” Pollacco said of the new planet-hunting program. “It’s
a great triumph for European astronomers.”

Fetal
planet

In addition
to the 10 new extrasolar recruits — the comprehensive exoplanet count now totals
277 — another group of astronomers said they’ve located an embryonic star
younger than any seen before with the Very Large Array of radio telescopes in New Mexico.

The group,
led by Jane Greaves of the University of St. Andrews in Scotland, found the 100,000-year-old fetal planet about 520 light-years away in the
constellation Taurus

“The new
object, designated HL Tau b, is the youngest planetary object ever seen,”
said Anita Richards, an astronomer at the U.K. Jodrell Bank Centre for
Astrophysics.

Richards,
who worked with Greaves’ team to describe the infant planet, said it’s just 1
percent as old as the young planet found in
orbit
around the star TW Hydrae last year.

“We
see a distinct orbiting ball of gas and dust, which is exactly how a very young
protoplanet should look,” Greaves said, noting the far-younger planet
should take on a Jupiter-like essence in millions of years.

Another
Earth?

Although
astronomers are developing large, space-based
projects
to hunt for Earth-like planets — such as the Jet Propulsion Lab’s
proposed Terrestrial Planet Finder — ground-based observers aren’t sitting idly
by.

In hopes of
finding small rocky planets, some U.K. astronomers are using a special camera
known as “RISE” that is mounted onto the Liverpool Telescope in England. The device rapidly photographs a portion of the sky and compares the brightness of
stars and large extrasolar planets from image to image.

If there’s any dimming, said Neale Gibson, also a QUB astronomer, the instrument will
find it and reveal if small rocky planets are disturbing the orbits of hot,
gassy planets.

“RISE
will allow us to observe and time the transits of extrasolar planets very
accurately,” Gibson said. “If Earth-mass planets are present in
nearby orbits … we will see their effect on the orbit of the larger transiting
planets.”


Source: imaginova



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