With new technique, astronomers find potassium in giant planet's atmosphere

Aug 31, 2010 by Tom Nordlie
This is a view of the Gran Telescopio Canarias in Spain’s Canary Islands. With its 10.4-meter diameter mirror, the telescope has more light-collecting area than any other. It was used by University of Florida astronomers to analyze light passing through the upper atmosphere of the giant planet HD 80606 b, about 190 light years from Earth, and determine that its atmosphere contains the element potassium. (Photo by: Miguel Briganti/SMM/IAC)

(PhysOrg.com) -- 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 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 ," said Knicole Colón, 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, arxiv.org, and have been submitted to the journals Astronomy & Astrophysics and the Monthly Notices of the Royal Astronomical Society. Colón 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 Colón'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 — Colón 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, Colón said.

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. Colón plans to search for in the atmospheres of additional 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 Colón want to examine smaller, Earth-like planets for molecules such as methane gas and water vapor, as both are intimately linked to life on .

Explore further: Quest for extraterrestrial life not over, experts say

Related Stories

UF astronomers pioneer new planet-observing technique

Jun 24, 2010

(PhysOrg.com) -- Using the world’s largest optical telescope, a team of University of Florida astronomers has pioneered a new method of observing planets outside our solar system. The method suggests that large Earth-based ...

Finding Twin Earths: Harder Than We Thought

Mar 20, 2009

(PhysOrg.com) -- Does a twin Earth exist somewhere in our galaxy? Astronomers are getting closer and closer to finding an Earth-sized planet in an Earth-like orbit. NASA's Kepler spacecraft just launched to ...

Hazy red sunset on extrasolar planet

Dec 11, 2007

A team of astronomers have used the NASA/ESA Hubble Space Telescope to detect, for the first time, strong evidence of hazes in the atmosphere of a planet orbiting a distant star. The discovery comes after ...

A New Way to Find Earths

Jul 09, 2010

Astronomers have used a completely new technique to find an exotic extrasolar planet. The same approach might even be sensitive enough to find planets as small as the Earth in orbit around distant stars.

Recommended for you

Quest for extraterrestrial life not over, experts say

Apr 18, 2014

The discovery of an Earth-sized planet in the "habitable" zone of a distant star, though exciting, is still a long way from pointing to the existence of extraterrestrial life, experts said Friday. ...

Continents may be a key feature of Super-Earths

Apr 18, 2014

Huge Earth-like planets that have both continents and oceans may be better at harboring extraterrestrial life than those that are water-only worlds. A new study gives hope for the possibility that many super-Earth ...

Exoplanets soon to gleam in the eye of NESSI

Apr 18, 2014

(Phys.org) —The New Mexico Exoplanet Spectroscopic Survey Instrument (NESSI) will soon get its first "taste" of exoplanets, helping astronomers decipher their chemical composition. Exoplanets are planets ...

User comments : 1

Adjust slider to filter visible comments by rank

Display comments: newest first

yyz
5 / 5 (3) Aug 31, 2010
These are some of the first observations of the atmospheres of exoplanets ever made, and as such are fascinating science as well as history in the making. Study of exoplanet atmospheres should lead to many new discoveries in this young field. Congratulations to both teams for successfully making these difficult observations. The papers described above can be found here:

http://arxiv.org/abs/1008.4800
http://arxiv.org/abs/1008.4795

More news stories

ISEE-3 comes to visit Earth

(Phys.org) —It launched in 1978. It was the first satellite to study the constant flow of solar wind streaming toward Earth from a stable orbit point between our planet and the sun known as the Lagrangian ...

Easter morning delivery for space station

Space station astronauts got a special Easter treat: a cargo ship full of supplies. The shipment arrived Sunday morning via the SpaceX company's Dragon cargo capsule.

Atom probe assisted dating of oldest piece of earth

(Phys.org) —It's a scientific axiom: big claims require extra-solid evidence. So there were skeptics in 2001 when University of Wisconsin-Madison geoscience professor John Valley dated an ancient crystal ...