Now in Sight: Far-Off Planets
- From: rst0wxyz <rst0wxyz@xxxxxxxxx>
- Date: Sun, 16 Nov 2008 06:57:55 -0800 (PST)
Now in Sight: Far-Off Planets
NASA, via Associated Press
A dust ring, seen in red, surrounds the star Fomalhaut, which is
located at the center of the image, but is not visible. The Hubble
Space Telescope captured a fuzzy image of the planet, known as
Fomalhaut b, which is no more than a white speck in the dust ring that
surrounds the star.
http://www.nytimes.com/2008/11/14/science/space/14planet.html?bl&ex=1226898000&en=034c0d653216eb42&ei=5087%0A
By DENNIS OVERBYE
Published: November 13, 2008
A little more of the universe has been pried out of the shadows. Two
groups of astronomers have taken the first pictures of what they say —
and other astronomers agree — are most likely planets going around
other stars.
The achievement, the result of years of effort on improved
observational techniques and better data analysis, presages more such
discoveries, the experts said, and will open the door to new
investigations and discoveries of what planets are and how they came
to be formed.
“It’s the tip of the iceberg,” said Christian Marois of the Herzberg
Institute of Astrophysics in Victoria, British Columbia. “Now that we
know they are there, there is going to be an explosion.”
Dr. Marois is the leader of a team that recorded three planets
circling a star known as HR 8799 that is 130 light-years away in the
constellation Pegasus. The other team, led by Paul Kalas of the
University of California, Berkeley, found a planet orbiting the star
Fomalhaut, only 25 light-years from Earth, in the constellation Piscis
Austrinus.
In an interview by e-mail, Dr. Kalas said that when he finally
confirmed his discovery last May, “I nearly had a heart attack.”
In scratchy telescope pictures released Thursday in Science Express,
the online version of the journal Science, the planets appear as fuzzy
dots that move slightly around their star from exposure to exposure.
Astronomers who have seen the new images agreed that these looked like
the real thing.
“I think Kepler himself would recognize these as planets orbiting a
star following his laws of orbital motion,” Mark S. Marley of the Ames
Research Center in Mountain View, Calif., wrote in an e-mail message
elaborating on HR 8799.
More than 300 so-called extrasolar planets have been found circling
distant stars, making their discovery the hottest and fastest-growing
field in astronomy. But the observations have been made mostly
indirectly, by dips in starlight as planets cross in front of their
home star or by wobbles they induce going by it.
Astronomers being astronomers, they want to actually see these worlds,
but a few recent claims of direct observations have been clouded by
debates about whether the bodies were really planets or failed stars.
“Every extrasolar planet detected so far has been a wobble on a
graph,” said Bruce Macintosh, an astrophysicist from Lawrence
Livermore National Laboratory in California and a member of Dr.
Marois’s team. “These are the first pictures of an entire system.”
The new planetary systems are anchored by young bright stars more
massive than our own Sun and swaddled in large disks of dust, the raw
material of worlds.
The three planets orbiting HR 8799 are roughly 10, 9 and 6 times the
mass of Jupiter, and orbit their star in periods of 450, 180 and 100
years respectively, all counterclockwise.
The Fomalhaut planet is about three times as massive as Jupiter,
according to Dr. Kalas’s calculations, and is on the inner edge of a
huge band of dust, taking roughly 872 years to complete a revolution
of its star.
Both systems appear to be scaled-up versions of our own solar system,
with giant planets in the outer reaches, leaving plenty of room for
smaller planets to lurk undetected in the warmer inner regions. Dust
rings lie even farther out, like the Kuiper belt of icy debris
extending beyond the orbit of Neptune.
“This is a window into what our own solar system might have looked
like when it was 60 million years old,” Dr. Marois said.
Sara Seager, a planetary theorist at the Massachusetts Institute of
Technology, said it was significant that the planets in both cases
seemed to be associated with disks of dust, particularly Fomalhaut,
one of the brightest and closest stars known to be host to a massive
disk.
“Fomalhaut is like a Hollywood star to astronomers, so we have some
personal excitement here,” Dr. Seager said. “It feels like finding out
that one of your four closest friends just won the lottery big time”
Alan Boss, a planetary theorist at the Carnegie Institution of
Washington, said the triple-planet system in Pegasus was particularly
promising, “as we expect planets to form in systems in general,
whereas spurious background interlopers will generally appear as
single ‘planets.’ ” But he and others cautioned that much more study
of these objects was necessary and that the masses imputed to them
were still highly uncertain.
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