a) Linewidths, Δv, of the ammonia (1, 1) lines (FWHP) measured toward the core L1251A. b) Mach numbers, M_s, of non-thermal motions at the 54 positions where T_kin was measured directly from the relative population of the (1, 1) and (2, 2) energy levels of NH₃. The contours are as in Fig. 3. The (0, 0) map position is as in Fig. 1.