vrijdag 12 juli 2013

NASA’s Spitzer Telescope Sees Super Earth

NASA’s Spitzer Space Telescope has detected light emanating from a “super-Earth” planet beyond our solar system for the first time. While the planet is not habitable, the detection is a historic step toward the eventual search for signs of life on other planets.
“Spitzer has amazed us yet again,” said Bill Danchi, Spitzer program scientist at NASA Headquarters in Washington. “The spacecraft is pioneering the study of atmospheres of distant planets and paving the way for NASA’s upcoming James Webb Space Telescope to apply a similar technique on potentially habitable planets.”

The planet, called 55 Cancri e, falls into a class of planets termed super Earths, which are more massive than our home world but lighter than giant planets like Neptune. Fifty-five Cancri e is about twice as big and eight times as massive as Earth. The planet orbits a bright star, called 55 Cancri, in a mere 18 hours.

Previously, Spitzer and other telescopes were able to study the planet by analyzing how the light from 55 Cancri changed as the planet passed in front of the star. In the new study, Spitzer measured how much infrared light comes from the planet itself. The results reveal the planet is likely dark and its sun-facing side is more than 2,000 Kelvin (3,140 degrees Fahrenheit), hot enough to melt metal.
The new information is consistent with a prior theory that 55 Cancri e is a water world: a rocky core surrounded by a layer of water in a “supercritical” state where it is both liquid and gas, and topped by a blanket of steam.

“It could be very similar to Neptune, if you pulled Neptune in toward our sun and watched its atmosphere boil away,” said Michael Gillon of Universite de Liege in Belgium, principal investigator of the research, which appears in the Astrophysical Journal. The lead author is Brice-Olivier Demory of the Massachusetts Institute of Technology in Cambridge.

The 55 Cancri system is relatively close to Earth at 41 light-years away. It has five planets, with 55 Cancri e being the closest to the star and tidally locked, so one side always faces the star. Spitzer discovered the sun-facing side is extremely hot, indicating the planet probably does not have a substantial atmosphere to carry the sun’s heat to the unlit side.

NASA’s James Webb Space Telescope, scheduled to launch in 2018, likely will be able to learn even more about the planet’s composition. The telescope might be able to use a similar infrared method as Spitzer to search other potentially habitable planets for signs of molecules possibly related to life.
“When we conceived of Spitzer more than 40 years ago, exoplanets hadn’t even been discovered,” said Michael Werner, Spitzer project scientist at NASA’s Jet Propulsion Laboratory (JPL) in Pasadena, Calif. “Because Spitzer was built very well, it’s been able to adapt to this new field and make historic advances such as this.”

In 2005, Spitzer became the first telescope to detect light from a planet beyond our solar system. To the surprise of many, the observatory saw the infrared light of a “hot Jupiter,” a gaseous planet much larger than the solid 55 Cancri e. Since then, other telescopes, including NASA’s Hubble and Kepler space telescopes, have performed similar feats with gas giants using the same method.

In this method, a telescope gazes at a star as a planet circles behind it. When the planet disappears from view, the light from the star system dips ever so slightly, but enough that astronomers can determine how much light came from the planet itself. This information reveals the temperature of a planet, and, in some cases, its atmospheric components. Most other current planet-hunting methods obtain indirect measurements of a planet by observing its effects on the star.

During Spitzer’s ongoing extended mission, steps were taken to enhance its unique ability to see exoplanets, including 55 Cancri e. Those steps, which included changing the cycling of a heater and using an instrument in a new way, led to improvements in how precisely the telescope points at targets.
JPL manages the Spitzer Space Telescope mission for NASA’s Science Mission Directorate in Washington. Science operations are conducted at the Spitzer Science Center at the California Institute of Technology (Caltech) in Pasadena. Data are archived at the Infrared Science Archive housed at the Infrared Processing and Analysis Center at Caltech. Caltech manages JPL for NASA.
For more information about Spitzer, visit: http://www.nasa.gov/spitzer

Source: http://beforeitsnews.com/space/2013/07/nasas-spitzer-telescope-sees-super-earth-2462782.html

Also See:

Image Caption: This illustration shows HD 189733b, a huge gas giant that orbits very close to its host star HD 189733. The planet's atmosphere is scorching with a temperature of over 1000 degrees Celsius, and it rains glass, sideways, in howling 7000 kilometre-per-hour winds. Credit: NASA, ESA, M. Kornmesser
Brett Smith for redOrbit.com – Your Universe Online
Using imagery from the Hubble Space Telescope, astronomers have determined that a planet orbiting a star close to our solar system has a deep azure blue color when seen from space, much like Earth.
The international team that made the discovery noted similarities between these two planets likely end at their color, as the exoplanet HD 189733b is being described as a gas giant with thousand degree temperatures and violent winds in its atmosphere.

Only 63 light years from Earth, HD 189733b is referred to as a “hot Jupiter,” a class of planets that resemble our solar system’s own gas giants but which orbit much closer to their sun than Saturn or Jupiter. It has been a recent planet of interest for Hubble and other telescopes.
“This planet has been studied well in the past, both by ourselves and other teams,” said Frederic Pont of the University of Exeter in the United Kingdom and a Hubble program leader. “But measuring its color is a real first – we can actually imagine what this planet would look like if we were able to look at it directly.”
According to the team’s report in Astrophysical Journal Letters, they were able to use the planet’s albedo, or light reflected off its surface, to determine its color. The planet’s reflected light was isolated from the light of its star using Hubble’s Space Telescope Imaging Spectrograph (STIS) to watch the entire system before, during and after the planet passed behind its star. When the planet passed behind the star, its reflected light was blocked from view, changing the dynamics of the entire system’s light being seen from Earth.

We saw the brightness of the whole system drop in the blue part of the spectrum when the planet passed behind its star,” explained co-author Tom Evans of the University of Oxford. “From this, we can gather that the planet is blue, because the signal remained constant at the other colors we measured.”

According to the team, the planet’s color comes not from blue oceans, but rather from a muddled, chaotic atmosphere filled with silicate particles which disperse blue light. The Hubble observations allowed the scientists to confirm previous theories about the planet’s blue color.
The colors of gaseous planets like Jupiter and Venus are due to unknown atmospheric particles. Earth, on the other hand, appears blue because the oceans strongly absorb red and green light and reflect the bluish hue of our sky, the scientists said.

“It’s difficult to know exactly what causes the color of a planet’s atmosphere, even for planets in the Solar System,” Pont said. “But these new observations add another piece to the puzzle over the nature and atmosphere of HD 189733b. We are slowly painting a more complete picture of this exotic planet.”

First discovered in 2005, HD 189733b is one of a number of hot Jupiters known to exist throughout the Universe. The planet is relatively close to Earth and unlike anything else in our own Solar System, making it an attractive object of study for researchers.
Source: Brett Smith for redOrbit.com - Your Universe Online

True Blue Planet And Its Turbulent Alien World - 2,000 Degrees Fahrenheit And Wind Speed 4,500-mph
MessageToEagle.com - Astronomers making visible-light observations with NASA's Hubble Space Telescope have deduced the actual color of a planet orbiting another star 63 light-years away.
The planet is HD 189733b, one of the closest exoplanets that can be seen crossing the face of its star.Hubble's Space Telescope Imaging Spectrograph measured changes in the color of light from the planet before, during and after a pass behind its star. There was a small drop in light and a slight change in the color of the light.

Click on image to enlargeExoplanet HD 189733b. Image Credit: NASA, ESA, and G. Bacon (STScI)

Click on image to enlargeThis artist's concept shows exoplanet HD 189733b orbiting its yellow-orange star, HD 189733. NASA's Hubble Space Telescope measured the actual visible-light color of the planet, which is deep blue. Image Credit: NASA, ESA, and G. Bacon (STScI)

"We saw the light becoming less bright in the blue but not in the green or red. Light was missing in the blue but not in the red when it was hidden," said research team member Frederic Pont of the University of Exeter in South West England. "This means that the object that disappeared was blue."

Earlier observations have reported evidence for scattering of blue light on the planet. The latest Hubble observation confirms the evidence.
If seen directly, this planet would look like a deep blue dot, reminiscent of Earth's color as seen from space. That is where the comparison ends.On this turbulent alien world, the daytime temperature is nearly 2,000 degrees Fahrenheit, and it possibly rains glass -- sideways -- in howling, 4,500-mph winds. The cobalt blue color comes not from the reflection of a tropical ocean as it does on Earth, but rather a hazy, blow-torched atmosphere containing high clouds laced with silicate particles.

Silicates condensing in the heat could form very small drops of glass that scatter blue light more than red light.
Hubble and other observatories have made intensive studies of HD 189733b and found its atmosphere to be changeable and exotic.HD 189733b is among a bizarre class of planets called hot Jupiters, which orbit precariously close to their parent stars. The observations yield new insights into the chemical composition and cloud structure of the entire class.

Click on image to enlargeThis plot compares the colors of planets in our solar system to exoplanet HD 189733b. The exoplanet's deep blue color is produced by silicate droplets, which scatter blue light in its atmosphere. Image Credit: NASA, ESA, and A. Feild (STScI)

Clouds often play key roles in planetary atmospheres. Detecting the presence and importance of clouds in hot Jupiters is crucial to astronomers' understanding of the physics and climatology of other planets.HD 189733b was discovered in 2005. It is only 2.9 million miles from its parent star, so close that it is gravitationally locked. One side always faces the star and the other side is always dark.In 2007, NASA's Spitzer Space Telescope measured the infrared light, or heat, from the planet, leading to one of the first temperature maps for an exoplanet. The map shows day side and night side temperatures on HD 189733b differ by about 500 degrees Fahrenheit. This should cause fierce winds to roar from the day side to the night side.

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