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The Cat's Eye Nebula
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Name: NGC 6543, Cat's Eye nebula, Snail Nebula, Sunflower Nebula, Caldwell 6
Description: White Dwarfs & Planetary Nebulas
Position (J2000): RA 17h 58m 33.30s Dec +66'° 37' 59.20"
Constellation: Draco
Distance: About 3,000 light years
Visual magnitude: 9.8
Scale: Image is 1.2 arcmin across. (about 1.7 light years)
Observation Dates: 10 May, 2000
Observation Time: 13 hours
Instrument: ACIS
Image Credit: X-ray: NASA/CXC/RIT/J.Kastner et al.; Optical: NASA/STScI
Release Date: October 10, 2012

Links to other images in the series:
Jan 1995    Jan 2001    Sept 2004    July 2008    Oct 2012

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From Wikipedia:

The Cat's Eye Nebula or NGC 6543, is a relatively bright planetary nebula in the northern constellation of Draco, which was discovered by William Herschel on February 15, 1786. It was notably the first planetary nebula whose spectrum was investigated by the English amateur astronomer William Huggins, demonstrating that planetary nebulae were gaseous and not stellar in nature. Structurally, the object has had high-resolution images by the Hubble Space Telescope revealing knots, jets, bubbles and complex arcs, being illuminated by the central hot planetary nebula nucleus or PNN. It is a well-studied object that has been observed from radio to X-ray wavelengths. (see's_Eye_Nebula for more information)

From Chandra:

This image is one of the planetary nebulae from the first systematic survey of such objects in the solar neighborhood made with NASA's Chandra X-ray Observatory. X-ray emission from Chandra is colored purple and optical emission from the Hubble Space Telescope is colored red, green and blue. (see rollover image for the x-ray composite)

A planetary nebula is a phase of stellar evolution that the Sun should experience several billion years from now. When a star like the Sun uses up all of the hydrogen in its core, it expands into a red giant, with a radius that increases by tens to hundreds of times. In this phase, a star sheds most of its outer layers, eventually leaving behind a hot core that will soon contract to form a dense white dwarf star. A fast wind emanating from the hot core rams into the ejected atmosphere, pushes it outward, and creates the graceful, shell-like filamentary structures seen with optical telescopes.

The diffuse X-ray emission seen in about 30% of the planetary nebulas in the new Chandra survey is caused by shock waves as the fast wind collides with the ejected atmosphere. The new survey data reveal that the optical images of most planetary nebulas with diffuse X-ray emission display compact shells with sharp rims, surrounded by fainter halos. All of these compact shells have observed ages that are less than about 5000 years, which therefore likely represents the timescale for the strong shock waves to occur.

About half of the planetary nebulas in the study show X-ray point sources in the center, and all but one of these point sources show high energy X-rays that may be caused by a companion star, suggesting that a high frequency of central stars responsible for ejecting planetary nebulas have companions. Future studies should help clarify the role of double stars in determining the structure and evolution of planetary nebulas.