NGC 6781 is a large circular planetary nebula in Aquila. The nebula is formed by an expanding shell of gas that is the ejected surface of a star during the latter stages of stellar evolution. The gasses forming the nebula fluoresce as a result of ultraviolet radiation from the magnitude 15.5 central star. When a star reaches this stage of evolution, it has burned its available hydrogen and helium. When a sun-like star's helium is gone, the core collapses into a white dwarf star. The remains of the star will eventually cool into oblivion after the ejected gas has dispersed into space. The magnitude 12.5 nebula has a size of 1.8 arc-minutes.
This is an RGB composite CCD image taken with an SBIG ST-8E CCD at prime focus on a Takahashi FCT-150 refractor operating at f7. The images were acquired using ACP and processed with MaxIm DL/CCD. This image was taken from my backyard in Scottsdale, Arizona.
RA: 19h 18m 44s Dec: +06d 32' 43"
April 23, 2005
Image by Sid Leach
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