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| Dust and the Helix Nebula | | | |
Dust makes this cosmic eye look red. This eerie Spitzer Space Telescope image shows infrared radiation from the well-studied Helix Nebula (NGC 7293), which is a mere 700 light-years away in the constellation Aquarius. The two light-year diameter shroud of dust and gas around a central white dwarf has long been considered an excellent example of a planetary nebula, representing the final stages in the evolution of a sun-like star.
Spitzer data show the nebula's central star is itself immersed in a surprisingly bright infrared glow. Models suggest the glow is produced by a dust debris disk. Even though the nebular material was ejected from the star many thousands of years ago, the close-in dust could be generated by collisions in a reservoir of objects analogous to our own solar system's Kuiper Belt or cometary Oort cloud. Formed in the distant planetary system, the comet-like bodies have otherwise survived even the dramatic late stages of the star's evolution. NASA
The Helix Nebula is an example of a planetary nebula created at the end of the life of a Sun-like star. The outer gases of the star expelled into space appear from our vantage point as if we are looking down a helix. The remnant central stellar core, destined to become a white dwarf star, glows in light so energetic that it causes the previously expelled gas to fluoresce.
Helix lies about 650 light-years away towards the constellation of Aquarius and spans about 2.5 light-years. Recent pictures of Helix are a composite of newly released images from the ACS instrument on the Hubble Space Telescope and wide-angle images from the Mosaic Camera on the WIYN 0.9 m Telescope at Kitt Peak National Observatory. It is estimated to be 10,600+2,300−1,200 years old based upon an expansion rate of 31 km/s. Wikipedia |
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