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With New Technique, University of Florida Astronomers Find Potassium in Giant Planet's Atmosphere
GAINESVILLE, Fla., Aug 31, 2010 (ASCRIBE NEWS via COMTEX) --
Any
driver who's seen deer silhouetted by the headlights of an
oncoming car knows that vital information can be conveyed by
the outlines of objects.
Building on this concept, University of Florida
astronomers have analyzed light passing through the upper
atmosphere of the giant planet HD 80606 b, about 190 light
years from Earth, and determined that its atmosphere
contains the element potassium.
"It's wonderful that this method works so well for
Jupiter-sized planets," said Knicole Colon, a UF astronomy
doctoral student. "Now, we're working to apply this
technique to observe smaller planets in an effort to
pinpoint the components of their atmospheres."
Coincidentally, another team led by David Sing at the
University of Exeter, in Devon, U.K., has just used the same
technique to detect potassium in the atmosphere of XO-2b,
another huge planet about 485 light years from Earth.
Both planets, known as gas giants, have extremely high
temperatures by earthly standards - HD 80606 b reaches about
2,200 degrees Fahrenheit and XO-2b is about 1,700
degrees. That's hot enough to vaporize potassium.
Together, these observations support previous computer
models that predicted what the atmospheres of such planets
would be like. The findings also demonstrate the value of a
new observational technique that could one day aid in the
characterization of planets that might support life. The two
groups' findings are available online at the arXiv preprint
server, http://arxiv.org , and have been submitted to thejournals
Astronomy & Astrophysics and the Monthly Notices of
the Royal Astronomical Society. Colon and Sing will present
their findings at the ExoClimes 2010 conference to be held
at the University of Exeter, Sept. 7-10.
The observational technique is called narrow-band transit
spectrophotometry, and it can measure the light absorbed by
the atoms and molecules in a planet's atmosphere, said Eric
Ford, a UF astronomy associate professor and Colon's
adviser.
"This new technique only works for planets that pass in
front of their parent stars as viewed from Earth. Most of
the nearly 500 known planets do not, and even fewer orbit
stars that are bright enough for such precise observations,"
Ford said. "Another challenge is that observations must be
carefully timed, in order to see the planets in silhouette
against the backlighting of their parent star."
Transit spectrophotometry works like this: While the
planet is backlit, astronomers measure the light that passed
through its atmosphere. Atoms and molecules absorb specific
wavelengths (colors) of light, providing a chemical
signature that scientists can recognize. By analyzing the
amount of absorption by the planet's atmosphere at specific
wavelengths, astronomers can detect the presence of a
particular atom or molecule - in this case, potassium.
The UF team -- Colon and Ford, along with colleagues from
the University of California, Santa Cruz, Penn State
University, Wesleyan University and the Universidad de La
Laguna in Tenerife, Spain -- had help from another
technological breakthrough.
These researchers, as well as the Exeter team, used one
of the world's most powerful telescopes, the Gran Telescopio
Canarias. The observatory includes a mirror almost 35 feet
wide and is situated at one of the world's best locations
for star-gazing, in the Canary Islands off the northwest
coast of Africa. UF is a 5 percent partner in the enormous
telescope, that captures enough light to make transit
spectrophotometry possible, Colon said.
(EDITORS: STORY MAY END HERE)
Sing says he's excited about future prospects for transit
spectrophotometry.
"The initial results from both teams have been very
encouraging," Sing said. "We still haven't explored the full
capabilities or ultimate limitations of the instrument yet."
In 2002, the Hubble Space Telescope detected a similar
element, sodium, in the atmosphere of the gas giant planet
HD 209458 b. Since then, astronomers have detected sodium in
only one other planet. Colon plans to search for potassium
in the atmospheres of additional giant planets to learn
about the diversity of planetary atmospheres. She hopes that
planet searches such as NASA's Kepler Mission will identify
many more planets that cross the faces of their parent
stars.
"The Kepler Mission has the precision to find even more
planets, including some as small as the Earth," she
said. Ultimately, Ford and Colon want to examine smaller,
Earth-like planets for molecules such as methane gas and
water vapor, as both are intimately linked to life on Earth.
ABOUT THE UNIVERSITY OF FLORIDA
The University of Florida is one of the nation's largest
public universities. A member of the Association of
American Universities, UF receives more than $550 million
annually in sponsored research funding. Through its
research and other activities, UF contributes more than $6
billion a year to Florida's economy and is responsible for
generating more than 77,000 jobs
statewide. http://www.ufl.edu . University of Florida
Research; Working for Florida.
- - - -
CONTACTS:
Writer: Tom Nordlie, 352-273-3567, tnordlie@ufl.edu
Sources: Eric Ford, 352-392-2052, eford@astro.ufl.edu
Knicole Colon, 609-284-2455, knicole@astro.ufl.edu
NOTE: Image available
http://news.ufl.edu/2010/08/31/potassium-planet/
((AScribe - The Public Interest Newswire / http://www.ascribe.org))
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