Grain temperature difference for four types of silicate grains as a function of their average T_d,0.1. The numbers in the legend indicate the size in μm. For comparison, the only-size-dependent T_d employed by our model is also shown, with exponent y=1/6. (The case with y=−1/6 is almost identical, with the large- and small-grain lines swapping places.) The value of T_d,0.1 on the x-axis practically depends on the amount of radiation received (or, therefore, on the distance) from the protostar.