Panel A: computation domain characteristic of the neck region. The top area (surface) is 1 cm² while the height is chosen larger than the diurnal skin depth, which is on the order of one centimeter. Self-heating between thefacets of the surface is taken into account. Panel B: illustration of the vertical structures assumed in this work. Left panel: dust mantle at the top (5 millimeters) and beneath a mixture of dust and water ice (blue spheres) with thermal inertia 36 TIU (model M1; derived from the method described in Sect. 6) and 100 TIU (model M2). Right panel: no dust mantle, with direct exposure of the dust-ice mixture layer (model M3).