Integrated intensity contours in ¹³CO 1–0 (green) and in [C i] (yellow) on top of a Spitzer IRAC false-colour image, composed of logarithmic intensities in the 8 μm channel (red), the 5.8 μm channel (green), and the 3.6 μm channel (blue). The contours are labelled with intensities [K km s^-1] integrated from 30 to 41 km s^-1. The positions of the submm cores P1, P2, and EP (from west to east) identified by Ormel et al. (2005) and the southern 24 μm source S2 from Van der Wiel & Shipman (2008) are indicated by asterisks. The circle indicates the beam size of the [C i] observations, the ¹³CO data are smoothed to the same resolution.