Fig. 5
Melting temperature on the sulfur-rich side of eutectic. Melting temperature of FeS (solid black line) and Fe–FeS eutectic (dashed black line) as a function of pressure. FeS data are from Boehler (1992) and Fe–FeS eutectic from Fei et al. (1997, 2000). Dotted lines are melting temperatures for different sulfur contents, obtained by linear interpolation between the melting temperatures of FeS and Fe–FeS eutectic. a corresponds to the pressure range of Ganymede’s core and (b) corresponds to the pressure range of the Moon’s core. Blue solid lines correspond to adiabatic temperature profiles and white circles indicate the point where melting and core temperatures coincide first during cooling, i.e., where crystallization of FeS starts. The adiabatic temperature profiles have been calculated for α = 9 × 10−5 K−1, ρ = 5500 kg m−3, cp = 830 J kg−1, g = 1 m s−2 (Ganymede), and α = 9 × 10−5 K−1, ρ = 5500 kg m−3, cp = 830 J kg−1, g = 0.6 m s−2 (Moon). Depending on the sulfur content, for Ganymede, FeS starts to crystallize in the core or at the CMB and for the Moon, FeS starts to crystallize in the core or in the core center