Category Archives: spitzer space telescope

astronomy, exoplanets, Kepler mission, Kepler-7b, spitzer space telescope

Exoplanet Cloud Atlas

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Patchy Clouds on a Distant World

Even though it’s not doing any more planet-searching due to an equipment failure, the Kepler telescope (along with the Spitzer Space Telescope) have returned data about a distant exoplanet called Kepler-7b that show it has clouds in its atmosphere. The data allowed astronomers to create an atlas of cloud forms over this planet, ranging from high clouds and clear skies in the western to somewhat clearer regions elsewhere. This is the first time that a “reflective signature” (that is, data that indicate reflectivity of an object in space) has been seen.

Kepler-7b (left), which is 1.5 times the radius of Jupiter (right), is the first exoplanet to have its clouds mapped. The cloud map was produced using data from NASA's Kepler and Spitzer space telescopes. Image credit: NASA/JPL-Caltech/MIT
Kepler-7b (left), which is 1.5 times the radius of Jupiter (right), is the first exoplanet to have its clouds mapped. The cloud map was produced using data from NASA’s Kepler and Spitzer space telescopes. Image credit: NASA/JPL-Caltech/MIT

Kepler-7b planet radiates much more heat than most giant planets that Kepler scientists have found and its reflectance definitely implies clouds. It lies much too far away from its star to account for the light scientists see being reflected by the planet. That almost certainly suggest that there are clouds floating in this world’s upper atmosphere.

During its mission, Kepler identified planets by fixing its gaze at a specific point in the sky and watching for dips in starlight that occur as the planets transit, or pass in front of their stars, blocking the light. This technique and other observations of Kepler-7b previously revealed that it is one of the puffiest planets known. If it could somehow be placed in a tub of water, it would float. The planet was also found to whip around its star in slightly less than five days, giving it a very short year.

Kepler’s partner in the observations of Kepler-7b, the Spitzer Space Telescope, can focus on one part of the sky for long periods of time, just as Kepler was designed to do. Spitzer is sensitive to infrared light which means it can “see” the heat coming from a distant object and take its temperature. During its observation, Kepler detected a temperature for Kepler-7b somewhere between 1,500 and 1,800 degrees Fahrenheit. Much hotter than most household ovens.

Using the two of these telescopes together to observe distant worlds gives astronomers a new way to study planets that lie far away circling other stars. It also allows astronomers to fine-tune their search for clouds on smaller, Earth-like worlds. (If you’re interested in more details you can read more about this discovery here.)

Now that Kepler is no longer actively looking for planets, scientists are turning their attention to the immense amount of data Kepler sent back, and using telescopes such as Spitzer (and ground-based instruments) to do observations on already known planet candidates.

I find it amazing that we can see these clouds on such a distant world (it lies trillions of miles from Earth). But, I find really impressive is that even though Spitzer can no longer do the most sensitive observations (due to its losing its instrument coolant), it can definitely still show us some amazing things in the cosmos. There are many more planet candidates discovered by Kepler that scientists will be studying, so look for more Kepler-based announcements in the foreseeable future.

astronomy, astronomy news, astronomy research, Infrared astronomy, spitzer space telescope

Come With Me to the Starry City

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And View it in Waves of Infrared Light

Astronomy takes you out there, thataway — and takes your breath away with cosmic visions of loveliness.  If it weren’t for the tools of astronomy that populate our spaceship of exploration, we’d still be seeing the universe in the equivalent of “black and white” TV of mid-last-century.  Those tools, like the Spitzer Space Telescope, with its infrared-sensitive detectors, open up the multi-wavelength universe and let us see things we weren’t able to see before.  Like the North American Nebula, in the constellation Cygnus, the Swan. Spitzer has just released some gorgeous imagery of this formerly mysterious region of space.

The first human to see the North American Nebula was William Herschel, back in 1786. It was merely a smudge to him, as it would be to anyone with a similar type of small telescope like he used.  I once tried to look at this nebula through a pair of fairly strong binoculars and through an 8-inch telescope, and it was faint, indeed. But, the shape of the nebula could be made out — it really does look like the outline of the North American continent.  However, this have changed since Herschel’s day. Today, we have telescopes and spacecraft that can look at wavelengths of light beyond the visible. Those have changed our perceptions of the cosmos.

Actually, what’s really changing is what we’re now able to see.  We’re detecting MORE of what’s in the nebula.  So, for example, we’re seeing infrared radiation given off by hot gas, for one thing. Inky black dust features seen in visible light are also heated, and they start to glow in the infrared view.

Different colors display different parts of the spectrum in each of these images. In the visible-light view (upper right) from the Digitized Sky Survey, colors are shown in their natural blue and red hues. The combined visible/infrared image (upper left) shows visible light as blue, and infrared light as green and red. The infrared array camera (lower left) represents light with a wavelength of 3.6 microns as blue, 4.5 microns as green, 5.8 microns as orange, and 8.0 microns as red. In the final image, incorporating the multi-band imaging photometer data, light with a wavelength of 3.6 microns has been color coded blue; 4.5-micron light is blue-green; 5.8-micron and 8.0-micron light are green; and 24-micron light is red.

This swirling landscape of stars is known as the North America nebula. In visible light, the region resembles North America, but in this new infrared view from NASA's Spitzer Space Telescope, the continent disappears. Where did the continent go? The reason you don't see it in Spitzer's view has to do, in part, with the fact that infrared light can penetrate dust whereas visible light cannot. Dusty, dark clouds in the visible image become transparent in Spitzer's view. In addition, Spitzer's infrared detectors pick up the glow of dusty cocoons enveloping baby stars. Clusters of young stars (about one million years old) can be found throughout the image. Slightly older but still very young stars (about 3 to 5 million years) are also liberally scattered across the complex, with concentrations near the "head" region of the Pelican nebula, which is located to the right of the North America nebula (upper right portion of this picture). Some areas of this nebula are still very thick with dust and appear dark even in Spitzer's view. For example, the dark "river" in the lower left-center of the image -- in the Gulf of Mexico region -- are likely to be the youngest stars in the complex (less than a million years old).

In the bottom two images, only infrared light from Spitzer is shown — data from the infrared array camera is on the left, and data from both the infrared array camera and the multi-band imaging photometer, which sees longer wavelengths, is on the right. These pictures look different in part because infrared light can penetrate dust whereas visible light cannot.

If you look back up at the “visible light” image of the nebula, you’ll see that it’s tough to make out those baby stars and the dusty cocoons where they formed. This is because they’re hidden by dark clouds, which are transparent to infrared light. This lets us peek behind the veil of gas and dust that hides star birth from us.

Baby stars are just part of the scene in the Spitzer image. We can see everything from the stellar cocoons where stars form to newborn stars sporting active jets to so-called “young adult” stars that are becoming more stable, and more capable of sustaining planetary systems.

There’s more to discover in this region of space. Not even Spitzer could reveal all the North American Nebula’s secret, hidden objects. Some of its clouds are just too dense for infrared to penetrate.  And, Spitzer now has no coolant left to chill down its detectors, so some of the longest wavelengths of infrared that it used to be able to detect are no longer available to it. But, that’s not stopping astronomers from studying these images and data. There’s still much to  learn from these observations. Stay tuned!