Distributions of young stars and molecular gas. (a) l–b distribution of YSOs (magenta circles) and young cluster members (white star symbols) overlaid on the ¹²CO (blue) and ¹³CO (green) intensity maps. The big circles are three Hα bubbles and a H I shell depicted in Figure 1 of G. A. Romero & C. E. Cappa (2009). (b) Histograms of distances of YSOs (magenta) and young cluster members (white). (c) Proper motion distributions of YSOs and young cluster members.