Description:
Abell 39 is a nearly perfect spherical planetary nebula located about 6,800 light-years away in the constellation Hercules. Formed from the outer layers of a dying star, it is notable for its symmetry and low surface brightness. The central star, slightly off-center, is extremely hot at around 89,000 K.
Abell 39 is especially valuable to astronomers for studying the late stages of stellar evolution due to its simple, clean structure and well-defined shell.