Detailed 870 μm continuum emission maps of Cha I extracted from the map shown in Fig. 2. The flux density greyscale is shown on the right of each panel and labeled in Jy/21.2″-beam. It has been optimized to reveal the faint emission with a better contrast. The angular resolution of the map is shown in the lower left corner of each panel (HPBW = 21.2″). The white plus symbols and ellipses show the positions, sizes (FWHM), and orientations of the Gaussian sources extracted with Gaussclumps or fitted with GAUSS_2D in the filtered map shown in Fig. 5a. The sources are labeled like in the first column of Tables 6, 8, and 9. “C” stands for starless core (or Class 0 protostellar core) and “S” for YSO (Class I or more evolved). In the following, the contour levels are described with the parameter b = 36 mJy/21.2″-beam, i.e. about 3 times the rms noise level. a) Field Cha-North. The contour levels are  − b (in dotted blue), b, 2b, 3b, 4b, 5b, 6b, 9b, 12b, 18b, 24b and 30b. The white, thin cross marks the SEST position of Cha-MMS2 (Reipurth et al. 1996).