DWB 118 — Propeller Nebula (Simeis 57)

DWB 118, better known as the Propeller Nebula or Simeis 57, is a faint Hα emission nebula located in the rich Cygnus star fields. Its distinctive “propeller” shape is formed by three curved filamentary structures of ionized gas. The nebula is part of the DWB catalog compiled by Dickel, Wendker and Bieritz, listing numerous Hα regions in the northern Milky Way. With its low surface brightness, DWB 118 requires long narrowband exposures to reveal its delicate structure. It lies within the larger Cygnus complex shaped by massive stars, stellar winds and ancient supernova activity.