These observations were made by students in Astro 422. Apache Point Observatory's 3.5-m telescope, Winter 1997. Red indicates those regions where the gas is ionized once by the central star.
Green light arises in regions where the gas is doubly ionized.
The blue colors arise in regions in which the light is dominated by continuous emission, such as starlight. Click for a bigger image . On some monitors this bigger and brighter image might look even better. Red indicates those regions where the gas is ionized once by the central star. Green light arises in regions where the gas is doubly ionized.