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Planetary Nebula NGC 6369: The Little Ghost



NGC 6369 in V and I filters
[Image Courtesy of NASA and H. Bond (STScI)]

NASA's Hubble Space Telescope has caught a glimpse of a cosmic ghost, the glowing remains of a dying star called NGC 6369. The glowing apparition is known to amateur astronomers as the "Little Ghost Nebula," because it appears as a small, ghostly cloud surrounding the faint, dying central star.

When a star with a mass similar to that of our own Sun nears the end of its lifetime, it expands in size to become a red giant. The red-giant stage ends when the star expels its outer layers into space, producing a faintly glowing nebula. Many of the details of ejection process are not visible from ground-based telescopes because of the blurring produced by the Earth's atmosphere.

 
   

The remnant stellar core in the center sends out a flood of ultraviolet light into the surrounding gas. At larger distances from the star, one can see fainter wisps of gas that were lost from the star at the beginning of the ejection process.

Our own Sun may eject a similar nebula, but not for another 5 billion years. The gas will expand away from the star at about 15 miles per second, dissipating into interstellar space after some 10,000 years. After that, the remnant stellar ember in the center will gradually cool off for billions of years as a tiny white dwarf star, and eventually wink out.


NGC 6369 in the F658N ([N II]) filter