RCW 16

RCW 16, also known as Sh 2-311 and Gum 9, is a nebula ionized primarily by the stars HD 64568, HD 64315, and LSS 830. It includes NGC 2467 (the Mandrill Nebula) and star clusters Haffner 18 and Haffner 19. Located in the direction of the Pup OB1 and OB2 associations, the region features significant ionization activities. Haffner 18 comprises two clusters at varying distances, with only a part associated with the nebula. Distance estimates for RCW 16 vary, with figures ranging from 15800 to 20500 light years.