Quote:
Originally Posted by upriver
Yes, I introduced this idea from a different paper as part of my argument against the optical thickness explanation for the solar blackbody spectrum.
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Not unless you are a lot older than I thought. See
Chandrasekhar & Breen, 1946 (and the other installements in the 5 part series linked from there).
In any case, I think that the radiation is already thermal once it reaches the bottom of the photosphere from the deep interior. In cool stars like the sun, the free-free & bound-free transitions involving the H
- ion are the principle sources of opacity in the stellar atmosphere. But they don't create the thermal spectrum, rather they allow the spectrum to remain thermal, since it was already thermal at the base of the photosphere. Besides, the solar spectrum is only approximately thermal, since we are seeing emission simultaneousy from all parts of the photosphere, which are at different temperatures. That's why the sun us said to have an
effective temperature of about 5700 Kelvins.