ALBUQUERQUE, N.M. - The Hubble Space Telescope's infrared camera has returned its first pictures after having been revived in March by shuttle astronauts who installed a new cooling device. The photos show the camera, inoperable since 1999, is working better than before, astronomers said.
The device, called the Near Infrared Camera and Multi-Object Spectrometer (NICMOS), peers through dust to see objects and structures that are not visible to optical telescopes. It can also see deeper into the universe than other observatories.
The colorful new pictures, billed as test images and presented here at the 200th meeting of the American Astronomical Society, do not reveal any significant new science. But astronomers were nonetheless elated to have the space-based infrared facility operational again.
"This is really fantastic," said Anneila Sargent, a professor of astronomy at Caltech. Sargent, who is not directly involved in NICMOS, said its return to service is vital to her own work involving radio astronomy. Combining observations in various wavelengths, she said, allows for a more complete understanding of celestial objects and phenomena.
in visible light by Hubble's newly installed Advanced Camera for Surveys (ACS). NICMOS sees past the outer layers of the nebula's dust to reveal more dense concentrations of dust deeper down, painting a more three-dimensional picture of the pillar-like structure.Several previously unseen stars show up as yellow dots in the upper right of the new view. It is not known if the stars are in the nebula or behind it.
For a second picture, the infrared camera was combined with Hubble's optical ACS to photograph a cosmic collision involving four galaxies. The crash scene is about 1 billion light-years away.
The tangle, collectively known as IRAS 19297-0406, glows 100 times brighter than our Milky Way in infrared light, even though it is only about half the size of our galaxy. The brightness is caused by dust generated in the collision, astronomers said.
New stars, forming out of the collision, are seen in visible light in the combined image.
"We need both cameras to give us a complete picture of what is happening" in the final stages of the assembly of what will become a giant elliptical galaxy, said Daniela Calzetti, a researcher at the Space Telescope Science Institute, which operates Hubble for NASA.
A third new photograph shows an edge-on view of a galaxy called NGC 4013. Able to see through the dust of the galaxy's disk, NICMOS revealed a surprising bright gold ring at the heart of the galaxy that represents a region of intense star formation, Calzetti said. As gas falls toward the galactic center, it piles up, compresses, and stars are generated.
While there are other infrared telescopes on the ground, NICMOS has certain advantages for being above the Earth's atmosphere, Calzetti explained, and it is the only instrument capable of seeing into the heart of NGC 4013 with such clarity.
The new pictures do not involve true color. Because infrared light is not visible to the human eye, colors are applied to the various wavelengths that are recorded in the NICMOS observations. Just as with visible light, longer wavelengths are typically assigned red and blue is used for shorter wavelengths.
NICMOS was installed in 1997 and quit working in 1999 when the nitrogen ice used to cool the instrument ran out. Earlier this year, astronauts installed a new cooling system. While it took longer than expected to bring the camera back online, the cooling system is working exactly as planned, said Ed Cheng of NASA's Goddard Space Flight Center.
"The NICMOS instrument is working better than ever," Cheng said.
Calzetti said NICMOS is 30 to 40 percent more sensitive than before because operators now have more control over the temperature at which it runs.
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