My ED80 doubled is not right scope to shoot over PN, but PNs are my favorite objects and I could not resist to capture one of them
Image on Astrobin
Fullsize: Abell 39 O3LRGB
Atik383L, EFW2, SW ED80 PRO + 0.85x SW FFR на AZ-EQ6 c гидированием; гид — QHY5 + OAG.
Baader L: 25 x 180s;
Baader R: 19 x 180s;
Baader G: 19 x 180s;
Baader B: 29 x 180s;
Baader O3: 48 x 1800s;
Abell 39 is a low surface brightness planetary nebula in the constellation of Hercules. It is estimated to be about 6,800 light-years from earth. It is almost perfectly spherical and also one of the largest known spheres with a radius of about 2.5 light-years.
Its central star is slightly west of center by about 2″ or 0.1 light-years. This offset does not appear to be due to interaction with the interstellar medium, but instead, it is hypothesized that a small asymmetric mass ejection has accelerated the central star. The mass of the central star is estimated to be about 0.61 M☉ with the material in the planetary nebula comprising an additional 0.6 M☉. The central star is classified as a subdwarf O star.
This planetary nebula has a nearly uniform spherical shell. However, the eastern limb of the nebula is 50% more luminous than the western limb. Additionally, irregularities in the surface brightness are seen across the face of the shell. The source of the east-west asymmetry is not known but it could be related to the offset of the central star.
This planetary nebula has been expanding for an estimated 22,100 (+1700−1500) years, based on an assumed expansion velocity between 32 and 37 km/s and a 0.78 parsec radius.