"I am reminded of the jellyfish exhibition at the Monterey Bay Aquarium -- beautiful things floating in water, except this one is in space," said Edward (Ned) Wright, the principal investigator of the WISE mission at UCLA, and a co-author of a paper on the findings, reported in the Astronomical Journal.
This image composite shows two views of a puffy, dying star, or planetary nebula, known as NGC 1514. The view on the left is from a ground-based, visible-light telescope; the view on the right shows the object in infrared light, as seen by NASA's Wide-field Infrared Survey Explorer, or WISE.
Image credit: NASA/JPL-Caltech/UCLA/DSS
The object, known as NGC 1514 and sometimes the "Crystal Ball" nebula, belongs to a class of objects called planetary nebulae, which form when dying stars toss off their outer layers of material. Ultraviolet light from a central star, or in this case a pair of stars, causes the gas to fluoresce with colorful light. The result is often beautiful -- these objects have been referred to as the butterflies of space.
NGC 1514 was discovered in 1790 by Sir William Herschel, who noted that its "shining fluid" meant that it could not be a faint cluster of stars, as originally suspected. Herschel had previously coined the term planetary nebulae to describe similar objects with circular, planet-like shapes.
Planetary nebulae with asymmetrical wings of nebulosity are common. But nothing like the newfound rings around NGC 1514 had been seen before. Astronomers say the rings are made of dust ejected by the dying pair of stars at the center of NGC 1514. This burst of dust collided with the walls of a cavity that was already cleared out by stellar winds, forming the rings.
"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 Laboratory in Pasadena, Calif., and lead author of the Astronomical Journal paper. Ressler first became acquainted with the object years ago while playing around with his amateur telescope on a desert camping trip. "It's funny how things come around full circle like this."
WISE was able to spot the rings for the first time because their dust is being heated and glows with the infrared light that WISE can detect. In visible-light images, the rings are hidden from view, overwhelmed by the brightly fluorescing clouds of gas.
"This object has been studied for more than 200 years, but WISE shows us it still has surprises," said Ressler.
Infrared light has been color-coded in the new WISE picture, such that blue represents light with a wavelength of 3.4 microns; turquoise is 4.6-micron light; green is 12-micron light; and red is 22-micron light. The dust rings stand out in orange. The greenish glow at the center is an inner shell of material, blown out more recently than an outer shell that is too faint to be seen in WISE's infrared view. The white dot in the middle is the central pair of stars, which are too close together for WISE to see separately.
Ressler says NGC 1514's structure, though it looks unique, is probably similar in overall geometry to other hour-glass nebulae, such as the Engraved Hourglass Nebula (http://hubblesite.org/newscenter/archive/releases/1996/07). The structure looks different in WISE's view because the rings are detectable only by their heat; they do not fluoresce at visible wavelengths, as do the rings in the other objects.
Serendipitous findings like this one are common in survey missions like WISE, which comb through the whole sky. WISE has been surveying the sky in infrared light since January 2010, cataloguing hundreds of millions of asteroids, stars and galaxies. In late September, after covering the sky about one-and-a-half times, it ran out of the frozen coolant needed to chill its longest-wavelength detectors. The mission, now called NEOWISE, is still scanning the skies with two of its infrared detectors, focusing primarily on comets and asteroids, including near-Earth objects, which are bodies whose orbits pass relatively close to Earth's orbit around the sun.
The WISE science team says that more oddballs like NGC 1514 are sure to turn up in the plethora of WISE data -- the first batch of which will be released to the astronomical community in spring 2011.
Other study authors are Martin Cohen of the Monterey Institute for Research in Astronomy, Marina, Calif.; Stefanie Wachter and Don Hoard of NASA's Spitzer Science Center at the California Institute of Technology in Pasadena; and Amy Mainzer of JPL.
JPL manages and operates the Wide-field Infrared Survey Explorer for NASA's Science Mission Directorate, Washington. The mission was competitively selected under NASA's Explorers Program managed by the Goddard Space Flight Center, Greenbelt, Md. The science instrument was built by the Space Dynamics Laboratory, Logan, Utah, and the spacecraft was built by Ball Aerospace & Technologies Corp., Boulder, Colo. Science operations and data processing take place at the Infrared Processing and Analysis Center at Caltech. Caltech manages JPL for NASA. More information is online at http://www.nasa.gov/wise and http://wise.astro.ucla.edu and http://www.jpl.nasa.gov/wise .
This image shows a puffy, dying star, or planetary nebula, known as NGC 1514. The object is actually a pair of stars, seen as a single dot at the center of the blue orb. One star is a dying giant somewhat heavier and hotter than our sun, and the other was an even larger star that has now contracted into a dense body called a white dwarf. As the giant star ages, it sheds some its outer layers of material. An inner shell of ejected material is seen in bright, light blues. An outer shell can also be seen in more translucent shades of blue.
NGC 1514 is located 800 light-years away, in the constellation Taurus. This image is from the Digitized Sky Survey, based at the Space Telescope Science Institute in Baltimore, Md.
Image credit: Digitized Sky Survey/STScI
A colorful creature in a starry sea stands out in this image from NASA's Wide-field Infrared Explorer, or WISE. The image shows infrared light that has been assigned visible colors we see with our eyes. The jellyfish-looking object is actually a very close pair of dying stars (white) surrounded by their shed material (green), and two very unusual dust rings (orange) discovered by WISE.
The object, named NGC 1514, is what is termed a planetary nebula. These are dying stars similar to our sun, that blow off their outer layers, sometimes forming beautiful, perfectly round orbs, and sometimes colorful butterfly shapes. In the case of NGC 1514, astronomers think there are two central stars orbiting each other; WISE cannot distinguish between the two stars, so only one white dot is seen. One star is an aging giant a bit warmer than our sun; the other was an even larger star that has already transformed into an ultra-hot white dwarf. The unusual rings, which are not quite like anything ever seen before around a planetary nebula, are thought to have formed when jets of material that were ejected from the white dwarf hit the walls of a bubble of dust around the stars. This bubble had previously been blown away from the giant star.
NGC 1514 was discovered in 1790 by Sir William Herschel, who was surprised to find what he called a "shining fluid" around the object. He had originally thought that it and all the other fuzzy-looking things he saw in the sky were clusters of stars, and that the telescopes he had were just not powerful enough to clearly see the individual stars. The discovery of NGC 1514 convinced Herschel that these fuzzy blobs were actually an unexpected astronomical phenomenon. Among this new class of objects were the "planetary nebulae" like NGC 1514 -- a term he had coined earlier to reflect their round, planet-like shapes.
NGC 1514 is located roughly 800 light-years away in the constellation Taurus, about 8 degrees (the width of a fist held at arm's length) away from the Pleiades star cluster. In this image, infrared light with a wavelength of 3.4 microns is blue; 4.6-micron light is cyan; 12-micron light is green; and 22-micron light is red.
Image credit: NASA/JPL-Caltech/UCLA
Contacts and sources:Whitney Clavin
Jet Propulsion Laboratory, Pasadena, Calif.