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Red (612-670nm)	Green (488-574nm)	Blue (392-508nm)

M27 Dumbbell Nebula

The negative image has been over exposed to reveal the faint detail that surrounds this planetary nebula - evidence of material ejected before the planetary phase? The positive RGB images are all linear and to the same scale. The negative images have been over exposed and stretched by the same amount. The red image is dominated by the Hydrogen alpha emission line (656.3nm) and the green and blue are both dominated by the Oxygen [III] emission line (500.7nm) which is passed by both filters. The white dwarf at the center of this planetary has a high surface temperature and is therefore blue - note how much fainter this central star is in the red image.

Note how the Mira type variable Star is bright in the red image, faint in the green and almost invisible in the blue.

Date	29th June 2006 (L), 30th June 2006 (RGB)
Telescope	250mm F4.8 Newtonian Reflector with coma corrector
Exposure (seconds)	12 x 300s Luminance 20 x 120s Red, 10 x 120s Green, 10 x 120s Blue