Helix nebula (NGC 7293)

This is the biggest planetary nebula seen from Earth, the Helix nebula. It's a medium sized star that explodes years ago, expanding the outer layers and keeping (left remanent) a white dwarf in the center. This is a L-Ha-RGB picture about 7hrs 28 minutes, 16 min subexposures 1x1, staked and procesed in Photoshop. The sky was poor with bad seeing and moderate airglow.