The Helix Nebula


helixnebulaThis infrared image taken by the Spitzer Space Telescope looks a bit like Sauron’s eye. It’s the Helix Nebula, a cosmic site often photographed by amateur astronomers because of its vivid colors and eerie resemblance to a giant eye. It’s about 700 light-years away in the constellation Aquarius and belongs to a class of objects called planetary nebulae.

Planetary nebulae are the remains of stars that were once like our Sun. When these stars die, they puff out their outer gaseous layers which are heated by the hot core of the dead star. The remnant becomes a white dwarf and shines with infrared and visible light. Our Sun probably will expand into a planetary nebula in around five billion years.

Spitzer‘s infrared view of the Helix nebula shows the outer gaseous layers is in blues and greens. The red color in the middle of the eye is the final layers of gas blown out when the star died. Blue shows infrared light of 3.6 to 4.5 µm wavelengths, green shows infrared light of 5.8 to 8 µm, and red shows infrared light of 24 µm.

The brighter red circle in the very center is the glow of the dust circling the white dwarf. This dust is thought to have been kicked up by comets that survived the death of the original star. Before the star died, its comets and possibly planets would have orbited the star in an orderly fashion. But when the star blew off its outer layers, it’s inner planets would have been swallowed up in its expanding shell, but the icy bodies and outer planets would have been stirred up and into tossed into each other, creating a cosmic dust storm. The Helix nebula is one of only a few dead-star systems in which evidence for cometary survivors has been found.

Image Credit: NASA

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