Hydrostatic and thermal equilibrium along the field line with zero gravity. The continuous line corresponds to Athays’s radiation function, the dashed line represents the results for Hildner’s function, while the background heatings are E₀ = 2.75 × 10⁻⁹ W m⁻³ and E₀ = 1.75 × 10⁻⁶ W m⁻³. In this particular example T₀ = 10⁴ K, ρ₀ = 10⁻¹¹ kg m⁻³, and the total length of the field line is 2L = 200 Mm. Model A is used in this plot.