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Planetary Nebula NGC 6826

NGC 6826's eye-like appearance is marred by two sets of blood-red FLIERs that lie horizontally across the image. The surrounding faint green "white" of the eye is believed to be gas that made up almost half of the star's mass for most of its life. The hot remnant star (in the center of the green oval) drives a fast wind into older material, forming a hot interior bubble which pushes the older gas ahead of it to form a bright rim. (The star is one of the brightest stars in any planetary.) NGC 6826 is 2,200 light- years away in the constellation Cygnus.

FLIERs stands for Fast Low-Ionization Emission Regions. They appear to be relatively young regions, moving outwards at supersonic speeds. According to Bruce Balick (University of Washington), "Some of their observed characteristics suggest that they are like sparks flung outward from the central star late in the very recent past (a thousand years ago). Yet their shapes ... seem to suggest that they are stationary, and that material ejected from the star flows past them, scraping gas from their surfaces. Future Hubble observations will monitor any changes in the positions of FLIERs to resolve this issue. In either case, the formation of FLIERs cannot be easily explained by any models of stellar evolution."

The planetary nebula NGC 3242 also has FLIERs.

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