Abell 39

The planetary nebula Abell 39 in the constellation Hercules is notable for its nearly perfect spherical shape. The sphere has a diameter of about 5 light-years, and the thickness of the glowing shell is roughly one-third of a light-year. The distance to the nebula, located in the constellation Hercules, is estimated at 7,000 light-years. It was discovered in 1966.

The central star associated with the nebula is offset from the center of the sphere by an angular distance of about 2″ (or 0.1 light-year). This offset currently lacks a clear scientific explanation, but it is thought to be caused by a slight asymmetry in mass during the star's explosion. The apparent magnitude of the star is 15.5m ± 0.2. The star's mass is about 0.61 M☉, and the nebula's gas mass is estimated at an additional 0.6 M☉. A noticeable asymmetry in the brightness of different parts of the nebula is also observed — opposite edges of the gas shell show a 50% difference in brightness, and brightness inhomogeneities are also visible across the disk in plan view.

According to estimates, the star's explosion occurred 22,100 +1,700 / −1,500 years ago, with the shell expanding at a speed of 32–37 km/s. The shell is quite transparent in the optical range, allowing background stars and galaxies to be observed through it.

This is my second imaging session in my own astro-pavilion with remote control.
The frames were taken between June 1 and June 15, 2026.

The brightness of the planetary nebula (L channel) was captured with a dual-band filter, while the color of everything, stars, and background objects were captured in RGB.