Spatial distribution of low-mass stars for three different extinction ranges: log N_H < 22.0 cm^-2 (upper panels), 22.0 cm^-2 < log N_H < 22.5 cm^-2 (middle panels), and log N_H > 22.5 cm^-2 (lower panels). Dashed contours represent dense gas traced by the integrated intensity emission of CN (N = 1–0) (Rodríguez-Franco et al. 1998). The first contour level corresponds to 7 K km s^-1, the interval between contours is 4 K km s^-1. The left panels show the position of the X-ray stars as blue dots. Four crosses, the open square, and the open triangle show the location of the four main sequence massive Trapezium stars, the OHC, and the OMC1-S. The right panels report the stellar surface density for the same extinction ranges, derived by counting the number of COUP sources using a cell size of 15′′ × 15′′ (0.03 pc × 0.03 pc) (right color scale), superimposed on the CN emission. The color contours have been smoothed for display purposes.