From: LARRY KLAES (ljk4_at_msn.com)
Date: Wed Oct 03 2007 - 09:33:26 PDT
>From: "AAS Press Officer Dr. Steve Maran" <Steve.Maran_at_aas.org>
>To: "AAS Press Officer Dr. Steve Maran" <steve.maran_at_aas.org>
>Subject: APL: Earth-like planet 'is likely forming 424 light-years away'
>Date: Wed, 3 Oct 2007 10:06:39 -0400
>
THE FOLLOWING RELEASE WAS RECEIVED FROM THE JOHNS HOPKINS UNIVERSITY APPLIED
PHYSICS LABORATORY, IN LAUREL, MARYLAND, AND IS FORWARDED FOR YOUR
INFORMATION. (FORWARDING DOES NOT IMPLY ENDORSEMENT BY THE AMERICAN
ASTRONOMICAL SOCIETY.) Steve Maran, American Astronomical Society
steve.maran_at_aas.org 1-202-328-2010 x116
For Immediate Release October 3, 2007
Media Contact:
Michael Buckley
1-240-228-7536 or 1-443-778-7536
Michael.Buckley_at_jhuapl.edu
Science Contact:
Dr. Carey Lisse
1-240-228-0535 or 1-443-778-0535
Carey.Lisse_at_jhuapl.edu
Note to editors: an image to accompany this release is available at:
http://www.jhuapl.edu/newscenter/pressreleases/2007/071003.asp
APL Astronomer Spies Conditions 'Just Right' for Building an Earth
An Earth-like planet is likely forming 424 light-years away in a star system
called HD 113766, say astronomers using NASA's Spitzer Space Telescope.
Scientists have discovered a huge belt of warm dust – enough to build a
Mars-size planet or larger – swirling around a distant star that is just
slightly more massive than our sun. The dust belt, which they suspect is
clumping together into planets, is located in the middle of the system's
terrestrial habitable zone. This is the region around a star where liquid
water could exist on any rocky planets that might form. Earth is located in
the middle of our sun's terrestrial habitable zone.
At approximately 10 million years old, the star is also at just the right
age for forming rocky planets.
"The timing for this system to be building an Earth is very good," says Dr.
Carey Lisse, of the Johns Hopkins University Applied Physics Laboratory,
Laurel, Md. "If the system was too young, its planet-forming disk would be
full of gas, and it would be making gas-giant planets like Jupiter instead.
If the system was too old, then dust aggregation or clumping would have
already occurred and all the system's rocky planets would have already
formed."
According to Lisse, the conditions for forming an Earth-like planet are more
than just being in the right place at the right time and around the right
star – it's also about the right mix of dusty materials.
Using Spitzer's infrared spectrometer instrument, he determined that the
material in HD 113866 is more processed than the snowball-like stuff that
makes up infant solar systems and comets, which are considered cosmic
"refrigerators" because they contain pristine ingredients from the early
solar system. However, it is also not as processed as the stuff found in
mature planets and the largest asteroids. This means the dust belt must be
in a transitional phase, when rocky planets are just beginning to form.
How do scientists know the material is more processed than that of comets?
>From missions like NASA's Deep Impact – in which an 820-pound impactor
spacecraft collided with comet Tempel 1 – scientists know that early star
systems contain a lot of fragile organic material. That material includes
polycyclic aromatic hydrocarbons (carbon-based molecules found on charred
barbeque grills and automobile exhaust on Earth), water ice, and carbonates
(chalk). Lisse says that HD 113766 does not contain any water ice,
carbonates or fragile organic materials.
>From meteorite studies on Earth, scientists also have a good idea of what
>makes up asteroids – the more processed rocky leftovers of planet
>formation. These studies tell us that metals began separating from rocks in
>Earth's early days, when the planet's body was completely molten. During
>this time, almost all the heavy metals fell to Earth's center in a process
>called "differentiation." Lisse says that, unlike planets and asteroids,
>the metals in HD 113766 have not totally separated from the rocky material,
>suggesting that rocky planets have not yet formed.
"The material mix in this belt is most reminiscent of the stuff found in
lava flows on Earth. I thought of Mauna Kea material when I first saw the
dust composition in this system – it contains raw rock and is abundant in
iron sulfides, which are similar to fool's gold," says Lisse, referring to a
well-known Hawaiian volcano.
"It is fantastic to think we are able to detect the process of terrestrial
planet formation. Stay tuned — I expect lots more fireworks as the planet
in HD 113766 grows," he adds.
Lisse has written a paper on his research that will be published in an
upcoming issue of Astrophysical Journal; he will also present his findings
next week at the American Astronomical Society Division for Planetary
Sciences meeting in Orlando, Fla. Lisse's research was funded through a
Johns Hopkins Applied Physics Laboratory Stuart S. Janney Fellowship and a
Spitzer Space Telescope guest observer grant.
NASA's Jet Propulsion Laboratory, Pasadena, Calif., manages the Spitzer
Space Telescope mission for NASA's Science Mission Directorate, Washington.
Science operations are conducted at the Spitzer Science Center at the
California Institute of Technology, also in Pasadena. Caltech manages JPL
for NASA. The University of Maryland is responsible for overall Deep Impact
mission science, and project management is handled by JPL.
The Applied Physics Laboratory, a division of The Johns Hopkins University,
meets critical national challenges through the innovative application of
science and technology. For more information, visit www.jhuapl.edu
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