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The region around the bright star Sadr (γ Cygni) is rich in faint, extended emission nebulae. Among them is the "Propeller Nebula" DWB 111, or Simeis 57, located about 4° to the north-northwest of Sadr. It is not yet known which star is responsible for the luminous excitation. The origin of this peculiar structure is unknown. The nebula's distance and source of excitation are also undetermined. Simeis 57 was discovered in the early 1950s.
LBN 242 and Surrounding Nebulosity, Western Cygnus, telelens photograph.
DWB 111 - Propeller Nebula in Hα, which is part of this image.
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