If we look back at Figure 3, we see that at ~0.83 R the density has achieved that of liquid hydrogen due to the gravitational force.

Additional pressure will then ionize the [deepest] hydrogen [by compressive ionization], creating a layer of positive charge.

For this reason, the top of the primary positive layer is set there (i.e., 125 Mm below the surface).

Due to the helioseismic echo at the tachocline, the bottom of that layer is set 84 Mm deeper.

All of the electrons expelled from the primary positive layer will congregate above, creating a negative layer.

The positive layer at the top [called the photosphere] can only be the result of induction [by the negative layer below].

Its depth is set at 20 Mm due to the presence of a slight helioseismic echo there.

[So the top layer, positive, ends at 20 Mm, the second layer, negative, ends at 125 Mm and the third layer, positive, ends at 209 Mm.]

Hence by fully processing a few simple facts, we gain a lot of information about the structure of the Sun, at least near the surface.

The remainder of this work applies this general method, of going back to the most salient observations of the Sun, and thoroughly considering the implications.

The result is a fully physical model that performs [well] at a high specificity.

References

1. Robitaille, P., 2011: On the Presence of a Distinct Solar Surface: A Reply to Hervé Faye. Progress in Physics, 3: 75-78

2. Robitaille, P., 2007: A High Temperature Liquid Plasma Model of the Sun. Progress in Physics, 1: 70-81

3. Picone, J. M.; E. Hedin, A.; Drob, D. P.; Aikin, A. C., 2002: NRLMSISE-00 empirical model of the atmosphere: Statistical comparisons and scientific issues. Journal of Geophysical Research, 107 (A12): 1468

4. Saumon, D.; Chabrier, G., 1992: Fluid hydrogen at high density: Pressure ionization. Physical Review A, 46 (4): 2084-2100