Thursday, May 29, 2025

RCW 75, also cataloged as Gum 51 or Henize 2-11, is an emission nebula located in the constellation Centaurus, approximately 9,000 light-years away. It is an active H II region, illuminated by newly formed massive stars that ionize the surrounding gas, producing intense emissions — especially in the Hydrogen-alpha (Hα) band. The structure of the nebula reveals bubble-like formations, sculpted by stellar winds and ultraviolet radiation from young stars, creating striking contrasts between bright regions and darker absorption zones. Its appearance varies depending on the filters used, but Hα emission dominates the scene, while SII and OIII highlight subtle details along the edges and inner cavities.