RCW 104 is a ring nebula around the Wolf Rayet star WR 75 in the constellation Norma; it is also ionized by the supergiant stars HD 147318 and HD 147617. The nebula features multiple knots of high speed gas at the filamentary edge. The image also shows multiple areas of high speed ejecta.
There is a very good article describing the formation of ring nebulae around Wolf Rayet stars by Reiner Vogel http://www.reinervogel.net/index.html?/WR/WR_e.html
Imaged in SHO narrowband and RGB for star color on our Planewave CDK 700 at Observatorio El Sauce, Chile.
Image acquisition and processing: Mike Selby