Velocity dispersion in Orion A. Top: PV-diagram (v_LSR vs l) for CO gas and YSOs in Orion A (see also Fig. 2). The blue error bars represent the one-sigma velocity dispersion of the gas for each line of sight. Over-plotted are the YSOs (orange) and their velocity dispersion per region (red bars) for comparison. Bottom: sigma map, showing the velocity dispersion for each pixel in blue color scale. Over-plotted are the YSOs as orange dots. The velocity dispersion variations show that there are regions with relatively higher σ (dark-blue). Such regions often correspond to cluster regions or regions of higher column-density. See Fig. 2 and text (Sect. 2.2) for more explanations.