heat of fusion - This is the heat content that must be added to a substance in order to melt it at constant pressure and temperature, or conversely, the heat content that is released from a substance as it solidifies from a liquid.
heat capacity - This is the quantity of heat required to raise the temperature of a substance by 1 degree at constant pressure or constant volume.
endothermic - This is a process that absorbs heat (such as the melting of water ice).
exothermic - This is a process that releases heat (such as dehydration reactions).
metal-troilite eutectic - This is the lowest-temparture melt that would occur in a chondrite. It corresponds to a temperature of ~990 degrees C (~1260 K).
Temperature contours in Fig. 3, 4 and 5 of the paper were not explicitly given but appear to be in degrees Kelvin.