PASADENA, Calif. -- A diverse cast of cosmic characters is showcased in the first survey images NASA released Wednesday from its Wide-field Infrared Survey Explorer, or WISE. Since WISE began its scan of the entire sky in infrared light on Jan. 14, the space telescope has beamed back more than a quarter of a million raw, infrared images. Four new, processed pictures illustrate a sampling of the mission's targets -- a wispy comet, a bursting star-forming cloud, the grand Andromeda galaxy and a faraway cluster of hundreds of galaxies.
WISE has worked superbly," said Ed Weiler, associate administrator of the Science Mission Directorate at NASA Headquarters in Washington. "These first images are proving the spacecraft's secondary mission of helping to track asteroids, comets and other stellar objects will be just as critically important as its primary mission of surveying the entire sky in infrared."
One image shows the beauty of a comet called Siding Spring. As the comet parades toward the sun, it sheds dust that glows in infrared light visible to WISE. The comet's tail, which stretches about 10 million miles, looks like a streak of red paint. A bright star appears below it in blue.
"We've got a candy store of images coming down from space," said Edward (Ned) Wright of UCLA, the principal investigator for WISE. "Everyone has their favorite flavors, and we've got them all."
During its survey, the mission is expected to find perhaps dozens of comets, including some that ride along in orbits that take them somewhat close to Earth's path around the sun. WISE will help unravel clues locked inside comets about how our solar system came to be.
Another image shows a bright and choppy star-forming region called NGC 3603, lying 20,000 light-years away in the Carina spiral arm of our Milky Way galaxy. This star-forming factory is churning out batches of new stars, some of which are monstrously massive and hotter than the sun. The hot stars warm the surrounding dust clouds, causing them to glow at infrared wavelengths.
WISE will see hundreds of similar star-making regions in our galaxy, helping astronomers piece together a picture of how stars are born. The observations also provide an important link to understanding violent episodes of star formation in distant galaxies. Because NGC 3603 is much closer, astronomers use it as a lab to probe the same type of action that is taking place billions of light-years away.
Traveling farther out from our Milky Way, the third new image shows our nearest large neighbor, the Andromeda spiral galaxy. Andromeda is a bit bigger than our Milky Way and about 2.5 million light-years away. The new picture highlights WISE's wide field of view -- it covers an area larger than 100 full moons and even shows other smaller galaxies near Andromeda, all belonging to our "local group" of more than about 50 galaxies. WISE will capture the entire local group.
The snowball-like mass of ice and dust spent billions of years orbiting in the deep freeze of the Oort Cloud, a spherical cloud of comets surrounding our solar system. At some point, it got knocked out of this orbit and onto a course that brings it closer to the sun. On October 7, 2009, it passed as close as 1.2 astronomical units from Earth and 2.25 astronomical units from the sun (an astronomical unit is the distance between the sun and Earth). Now, the comet is leaving the warmer, more hospitable neighborhood of the solar system and heading back out to chillier parts.
In this view, longer wavelengths of infrared light are red and shorter wavelengths are blue. The comet appears red because it is more than ten times colder than the surrounding stars, for example, the bright blue star in the foreground. Colder objects give off more of their light at longer wavelengths. An ice cube, for example, pours out a larger fraction of its light at longer infrared wavelengths than a cup of hot tea emits.
A comet like this one can be thought of as a time capsule leftover from the formation of our solar system 4.5 billion years ago. After spending most of its long, lonely life in the darkest, coldest parts of our solar system, it warms up as it approaches the sun. The sunlight causes it to shed ices and dust in a long tail that trails behind it.
Comet Siding Spring, having experienced this "spring" awakening, is glowing in infrared light that WISE can see. Once it moves too far from the sun's warmth and light, it will disappear from view for the foreseeable future.
Astronomers will use these measurements to learn about the comet's size, composition, reflectivity, and the size and makeup of the dust particles in its coma (the hazy cloud surrounding its nucleus) and its tail. WISE data on this and other comets will help unlock clues that lay within these icy time capsules, teaching us about our solar system's evolution.
In this image, 3.4-micron light is colored blue; 4.6-micron light is green; 12-micron light is orange; and 22-micron light is red. It was taken on Jan. 10, 2010.
WISE, which is surveying the whole sky in infrared light, is particularly sensitive to the warm dust that permeates star-forming clouds like this one. In this way, WISE complements visible-light observations.
The mission also complements Hubble and other telescopes by showing the 'big picture," providing context for more detailed observations. For example, the WISE picture here is 2,500 times larger than the Hubble inset. While the Hubble view shows the details of the hot young star cluster, the WISE picture shows the effects that this stellar powerhouse has on its neighborhood.
The cluster contains some of the most massive stars known. Winds and radiation from the stars are evaporating and dispersing the cloud material from which they formed, warming the cold dust and gas surrounding the central nebula. This greenish "halo" of warm cloud material is seen best by WISE due to its large field of view and improved sensitivity over past all-sky infrared surveys.
These WISE observations provide circumstantial evidence that the massive stars in the center of the cluster triggered the formation of younger stars in the halo, which can be seen as red dots. The dust at the center of the cluster is very hot, producing copious amounts of infrared light, which results in the bright, yellow cores of the nebulosity.
Ultimately, this turbulent region will be blasted apart by supernova explosions. Other star-forming clouds in the Milky Way have experienced such eruptions, as evidenced by their pockmarked clouds of expanding cavities and bubbles.
Massive star clusters like this one are an important link to understanding the details of the violent original epoch of massive star formation in the early, distant universe. Astronomers also use them to study distant starbursts that occur when galaxies collide, lighting up tremendous firestorms of brilliant, but ephemeral, stars in the wreckage. Because NGC 3603 is so close, it is an excellent lab for the study of such faraway and momentous events.
The mosaic covers an area equivalent to more than 100 full moons, or five degrees across the sky. WISE used all four of its infrared detectors to capture this picture (3.4- and 4.6-micron light is colored blue; 12-micron light is green; and 22-micron light is red). Blue highlights mature stars, while yellow and red show dust heated by newborn, massive stars.
Andromeda is the closest large galaxy to our Milky Way galaxy, and is located 2.5 million light-years from our sun. It is close enough for telescopes to spy the details of its ringed arms of new stars and hazy blue backbone of older stars. Also seen in the mosaic are two satellite galaxies, known as M32, located just a bit above Andromeda to the left of center, and the fuzzy blue M110, located below the center of the great spiral arms. These satellites are the largest of several that are gravitationally bound to Andromeda.
The Andromeda galaxy is larger than our Milky Way and contains more stars, but the Milky Way is thought to perhaps have more mass due to its larger proportion of a mysterious substance called dark matter. Both galaxies belong to our so-called Local Group, a collection of more than 50 galaxies, most of which are tiny dwarf systems. In its quest to map the whole sky, WISE will capture the entire Local Group.
source . http://www.nasa.gov