RCW 40 is a rarely imaged faint emission nebula.
This HII region appears to be part of the Vela OB1 association and according to Avedisova is ionised by the O9 V star CD -48 4352.
The nebula contains a spectacular bubble structure.
Imaged in Ha OIII and RGB on my RiDK 400 at Observatorio El Sauce, Chile.
Image Acquisition and Processing: Mike Selby