Temperature equilibrium in a static gravitational field

In the case of a gravitating mass of perfect fluid which has come to thermodynamic equilibrium, it has previously been shown that the proper temperature T0 as measured by a local observer would depend in a definite manner on the gravitational potential at the point where the measurement is made. In the present article the conditions of thermal equilibrium are investigated in the case of a general static gravitational field which could correspond to a system containing solid as well as fluid parts. Writing the line element for the general static field in the form ds2=gijdxidxj+g44dt2 i,j=1,2,3, where the gij and g44 are independent of the time t it is shown that the dependence of proper temperature on position at thermal equilibrium is such as to make the quantity T0sqrt[g44] a constant throughout the system.