Core masses and core mass distribution. (a) Core masses derived using a density-dependent opacity (grains with no ice mantles) vs. masses derived using a constant dust opacity of 1.93 cm ² g⁻¹ (at 850 μm). The full line marks equal masses, whereas the dashed line marks density-dependent opacity masses equal to 70% of the constant density masses. (b) Core mass distributions for masses obtained with a constant dust opacity of 1.93 cm ² g⁻¹ (at 850 μm; full line) and for masses obtained with a density-dependent opacity (dashed line). The error bars have been computed assuming a Poisson statistics.