SEST observations. ¹²CO(1–0) line emission integrated over velocity intervals of 1 km s^-1 between 6 and 12 km s^-1. Lowest contour level and step are 1 K km s^-1. The observed positions are indicated in the lower panel. This panel also indicates the area observed with the SEST in ¹³CO(1–0). The filled circles indicate the positions of the candidate emission-line stars, which are labelled with their numbers as in Table 1. Offsets as in Fig. 2.