Abell 39

Abell 39 is a low surface brightness planetary nebula in the constellation of Hercules. It is estimated to be about 3,300 light-years from earth and 4,600 light-years above the Galactic plane. It is almost perfectly spherical and also one of the largest known spheres with a radius of about 1.3 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. This planetary nebula has been expanding for an estimated 22,100 years. Oxygen is only about half as abundant in the nebula as it is in our own sun. This was captured from my backyard on 19-20 July 2022.