Abell 39 (also known as PN A66 39 and PK 47+42.1) is the 39th entry in 1966 Abell Catalogue of Planetary Nebulae, compiled by George Abell in 1966 with data obtained from the Palomar Observatory Sky Survey (POSS).
It is a beautiful example of a planetary nebula, has a low surface brightness, and it is located in constellation Hercules. The distances of planetary nebulae are usually quite imprecise. In this case, the literature reports estimates ranging from 3300 to 7000 light-years.
The peculiarity of this nebula is that it has a practically spherical shape (with a radius of approximately 2.5 light-years). Another special characteristic of this nebula is that its central star (which is evolving into a hot white dwarf) is not perfectly centred, but slightly displaced to the west.
This is an LRGB image and accumulates more than 18 hours of exposure time. As in my previous planetary nebula image (M97), this object is relatively "small" for my equipment, which provides a resolution of 1.69"/pixel, so it has been processed with Drizzle Integration x2, obtaining a final image at 0.85"/pixel.
The image processing had to be very careful, trying to maintain some detail in the small (for the scale of the image) galaxies behind the planetary and in the rest of the sky background.
To try to achieve this goal, the image has been decomposed into its large-scale and small-scale components, which have been processed separately and recombined at the end.
Click on the image for a full resolution version, or go to the Gallery section for complete exposure details.
Image processing: Pixinsight.
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