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jueves, 18 de noviembre de 2010

Weird Ringed Nebula Glows in Infrared

NASA’s WISE infrared space telescope is losing its refrigeration, but its backlog of data is still yielding cool images such this one of an odd, blobby, jellyfish-like nebula.

“I just happened to look up one of my favorite objects in our WISE catalogue and was shocked to see these odd rings,” said Michael Ressler, a member of the WISE science team at NASA’s Jet Propulsion Lab, in a press release.

The object, called the “Crystal Ball” nebula or NGC1514, is a planetary nebula located 800 light-years away in the constellation Taurus. Planetary nebulas form when a dying star puffs off its outer layers of material and illuminates the gaseous cloud from within. They’re called “planetary” because the first such objects discovered were roughly spherical, like a planet, although nebulas with lopsided wings are now known to be common.

In visible light (left image), NGC 1514 looked a lot like any other asymmetrical nebula. But WISE’s infrared image (right) shows loopy rings surrounding NGC 1514 that are unlike anything astronomers had seen before.

“This object has been studied for more than 200 years, but WISE shows us it still has surprises,” Ressler said. The observations are reported Nov. 9 in the Astronomical Journal.

The rings could be dust ejected from a pair of dying stars at the nebula’s center, one a giant star heavier and hotter than the sun, the other a dense white dwarf. The giant star sheds some outer layers as it ages to form a bubble around the two stars. Jets of material from the white dwarf are thought to have smashed into the bubble, forming the rings that glow orange in the WISE image.

The green cloud is an inner shell of previously shed material, which shows up in light blue in the visible image.

The rings went undetected until WISE because their dust is heated and glows with the infrared light that WISE can detect. In this image, infrared light with a wavelength of 3.4 micrometers is blue; 4.6-micrometer light is turquoise; 12-micrometer light is green and 22-micrometer light is red. In visible-light images, the rings are washed out by the bright clouds of gas.

Many more surprises lurk in the piles of data WISE collected between January and October of this year. The first batch of data will be released to the astronomical community in spring 2011. Meanwhile, WISE — which ran out of coolant in late September and is now too warm for two of its infrared cameras to function — is continuing on as NEOWISE, searching for near-Earth objects like asteroids and comets.

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