Tests of the Solar Model

This is a tricky proposition because we cannot see the interior of the Sun in visible light. As a consequence, most of what we know about the interior of the Sun (and hence stars) comes from well-crafted theory which has been tweaked and improved through comparisons to observations.

Now let us pursue this issue in more detail.

• Given the equations of hydrostatic and thermal equilibrium one can calculate the structure of the Sun if one uses what we know about nuclear reactions, energy transport, how the pressure is generated, and some other properties of the Solar materials. Once we specify these things, it is a fairly straightforward exercise to calculate the structure of the interior of the Sun.

  The calculated structure of the Sun shown

  • in a Bullseye Diagram

  • Graphically

  The basic model of the Sun is constrained by because we have a very good idea of the mass of the Sun and we have good numbers for the luminosity and radius of the current Sun. However, this does not mean that we have the Sun nailed. For example, because we cannot see the core of the Sun, we can fiddle around a little with the assumed chemical composition of the core of the Sun. By tweaking some parameters, we can match the observed properties of the Sun. We would like to have more detailed tests of our theories theories of solar structure.

• Tests of our theories of stellar structure
  • Solar Neutrino Experiments
  • Solar Oscillations
    • The Sun is like a bell in the sense that if you kick it, it will ring (or oscillate). Furthermore, like a bell or a tuning fork, etc., the way in which the Sun rings (its pitch) is determined by the detailed interior structure of the Sun.
    • For the last 10 - 20 years, people have been studying Solar oscillations much as seismologists on the Earth study the ringing of the Earth after earthquakes.
    • The observations serve as nice checks on our ideas of the structure of the interior of the Sun.
    • I believe, however, that the observations have simply tuned up our understanding of the interior of the Sun and have not yet turned up anything startling like the Solar Neutrino Experiments.