The Ring Nebula, M57
The Ring Nebula (also catalogued as Messier 57, M57 or NGC 6720) is a planetary nebula in the northern constellation of Lyra. Such objects are formed when a shell of ionized gas is expelled into the surrounding interstellar medium by a red giant star, which was passing through the last stage in its evolution before becoming a white dwarf. Notice the outer 2 halos in HA and O3, you can see the negitives below.
Telescope: Planewave 24" f6.7 on a Planewave HD Mount Camera: SBIG 16803
Location: Stellar Winds Observatory at DSNM, Animas, New Mexico
Exposure: L,R,G,B,HA,03 500,500,500,500,900,900