Diagram showing the (v_LSR, l) distribution for different spiral tracers in the vicinity of Stephenson 2. Black circles represent red supergiants observed in our survey. Their size is proportional to the estimated E(J − K_S), as in Fig. 7. Diamonds are methanol masers (associated with star-forming regions) taken from Green et al. (2011). Asterisks represent H ii regions observed in radio (Anderson et al. 2011). Cluster members from D07 are shown as empty circles.