Abell 39

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 7000 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 copious amounts of UV radiation which excite the surrounding gas and make it fluoresce its green-blue color. Compare this image with another image (narrowband) of Abell 39 taken at the 3.5m WIYN telescope on Kitt Peak.

This image was taken as part of Advanced Observing Program (AOP) program at Kitt Peak Visitor Center during 2014.