|Abell 39 is perhaps one of the most perfect examples of a spherical
planetary nebula in the galaxy. As expected, a sphere of gas will show a
brighter limb ("edge") since that line of sight has more gas than the view
through the center (two layers) of the bubble. This one is unfortunately
very faint and subtle details of the bubble require a larger telescope
(or very long exposures) to bring out. Abell 39 is approximately 5 light
years across and 7,000 light years away. Note the myriad of background
galaxies in the image- especially through the transparent sphere of
gas. Also note that the central star is distinctly blue-white in color. A
blue-white color indicates that the central star (white dwarf) is very hot.
It emits copius amounts of UV radiation which excite the surrounding gas
and make it flouresce its green-
blue color. Compare this image with another image (narrowband)
of Abell 39
taken at the 3.5m WIYN telescope.
|L R G B color production was used to create this image.||
Minimum credit line: Adam Block/NOAO/AURA/NSF
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