The Propeller Nebula is located in the very large Cygnus X nebular complex. The Propeller is commonly referred to, somewhat incorrectly, as DWB 111. Actually DWB 111 is the lower portion of the Propeller and the upper portion is designated as DWB 119. A more accurate designation of the nebula, which would include the entire Propeller, is Simeis 57. The nebula is classified as an emission nebula and radiates strongly in Hydrogen Alpha (Ha), and to a lesser extent, in ionized Sulphur (SII), and weakly in doubly ionized Oxygen (OIII). The distance to the Propeller Nebula is somewhat unclear, but estimates to the Cygnus X complex is documented as approximately 4,600 light years.
The image above is known as a mapped, or false, color image and was acquired using narrowband filters. It was assembled using the standard Hubble Palette with SII mapped to red, Ha mapped to green and OIII mapped to blue. A Bi-Color (near true color) version of the image may be viewed here.