Abell 13 (known as the Onion ring nebula)[2] is a flarge and highly evolved planetary nebula located 3900 light years from Earth in the constellation of Orion.

[3] It has a reddish color and is very faint.

Abell 13 has a circular outer ring of Ha (Hydrogen-alpha).

[4] The nebula was discovered in 1955 by an American astronomer named George Ogden Abell on the photo plates of the Palomar Observatory Sky Survey (POSS).

This nebula-related article is a stub.