Radial profiles of various first core properties during the collapse of a 0.01 M_⊙ clump for a core central density ρ_c = 1.8 × 10^-11 g cm^-3, for calculations done with 4500 cells (dotted red line) and 18 000 cells (solid black line). From top left to bottom right: a) density; b) gas temperature; c) velocity; d) entropy; e) optical depth; f) luminosity.