Dynamics of the Solar Wind: Parker's Treatment and the Laws of Thermodynamics

In 1958, Eugene Parker proposed that the solar wind must be produced by thermal expansion of coronal gas.1 At the time, he advanced a dimensionless parameter, λ = GMSMH/2kBToa, where G corresponds to the universal constant of gravitation, MS to the solar mass, MH to the mass of the hydrogen atom, kB to Boltzmann’s constant, To to the temperature at the location of interest, and 'a' to the radial distance of that location from the center of the Sun. It is straightforward to demonstrate that this equation stands in violation of the zeroth and second laws of thermodynamics, by simply rearranging the expression in terms of temperature, To = GMSMH/2λkBa, in which case temperature, an intensive property, is being defined in terms of an extensive property, MS, and the radial position, 'a', which is neither intensive nor extensive. All other terms in this expression are constants and therefore unable to affect the character of a thermodynamic property. As a result, temperature in this expression is not intensive. Consequently, the expression advanced by Parker is not compatible with the laws of thermodynamics. This analysis demonstrates that solar winds cannot originate from the thermal expansion of coronal gas as currently accepted.

1Parker E.N. Astrophys. J., 1958, v. 128, 664-676.