Ghostly green eye

Planetary nebula NGC 6826

NGC 6826 is a planetary nebula, the dying stages of a star's life.

THIS AMAZING IMAGE shows the ghostly “eye-like” planetary nebula NGC 6826, located 2,200 light-years from Earth.

Despite their name, planetary nebulae have nothing to do with planets. They got their name because, through early telescopes, they looked more like planets than stars.

In fact, a planetary nebula is a complex cloud of gas produced in the dying stages of certain stars’ lives.

A star’s life ends when the fuel available to its thermonuclear engine runs out. When the star is about to expire, it becomes unstable and ejects its outer layers, forming a planetary nebula and leaving behind a tiny, but very hot, stellar remnant, known as white dwarf.

Schematic of NGC 6826

Anatomy of planetary nebula NGC 6826

At NGC 6826’s centre, the white dwarf is driving a fast “wind” of gas into older gas material, forming a hot interior bubble that pushes the older gas ahead of it to form a bright rim. The faint green of the eye is believed to be gas that made up almost half of the star’s mass for most of its life.

The red blobs at the edges are called FLIERs, or Fast Low-Ionisation Emission Regions. They’re thought to be dense regions of gas either flung off by the star, or floating in space and caught up in the outflowing rush of the stellar wind.

Stellar evolution theory predicts that our Sun will experience a similar fate to NGC 6826 in about five billion years (out of an estimated overall lifespan of some ten billion years).

And by the way, what does the NGC in its name stand for? The New General Catalogue is a huge list of more than 7,800 “deep space” objects compiled in 1880s by the Danish-Irish astronomer J.L.E. Dreyer.

Downloadable wallpaper image: 1280 x 1280

Adapted from information issued by Bruce Balick (University of Washington), Jason Alexander (University of Washington), Arsen Hajian (U.S. Naval Observatory), Yervant Terzian (Cornell University), Mario Perinotto (University of Florence, Italy), Patrizio Patriarchi (Arcetri Observatory, Italy) and NASA/ESA.

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