Quote:
Originally Posted by Arneb
I read in a popular science book by a respected German science journalist (some 25 years ago) that the core of the Sun is absolutely and utterly pitch black. |
Oooh, hmmmmm, uhhh. A muddy color is in the works. Is there a Solar Phsicist in the house?
The photon production in the core is primarily gamma rays as a result of the proton-proton reaction. I think there are several different energies of these produced in the chain. There are other high energy photons produced by the CNO process which constitutes only about 1% of the energy production. I don't know what might take place within the core that would produce much lower energy photons that would allow the production of photons that would fall in the optical range. So, my color view is starting to turn black.
But, I want to look at the core's "surface" and consider that the random walk of the photons is indeed random. Thus, photons of all energies can be found here since they are meandering in all directions, though more outward than inward. It is not until the temperature drops enough, when hydrogen can accept a second electron, that photons get trapped (ie the convective zone). Thus the inner sections allow radiative transfer, including the core.
There is also Doppler shifts due to the kinetic energy levels of the hydrogen in the core, though I won't bother calculating them.
So, thanks mainly to this sunny, photonic Volksmarsch, I will argue against a black core, for now. [It would still be pretty colorful if you are right, admittedly.
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For the sake of this question, and given the colorful spirit it was asked, let us assume a more blackbody result for the energy production of the core, at least along the outer boundary. You may further assume a 15 million degree temperature here.