The solar core is surrounded by the radiative zone, within which energy is carried by photons.  But the zone is a very dense plasma, so the photons scatter as they slowly diffuse outward.  This is actually conduction, but with photons rather than atoms as the heat carrier.  The photon density is proportional to T^4.  When the temperature drops sufficiently that the photons can no longer transport the required heat flux, then convection takes over the job.   --  Gene

________________________________ From: Bill Gosper <billgosper@gmail.com> To: math-fun@mailman.xmission.com Sent: Wednesday, January 1, 2014 4:30 PM Subject: [math-fun] Is this the Guinness record refraction index?

WDS>

It is estimated that heat produced in sun core takes 200K years to escape,   http://articles.adsabs.harvard.edu/full/1992ApJ...401..759M/0000760.000.html since the sun's gas is a thick layer of insulation that slows down radiative transfer.<WDS

"The average velocity of the photon between the center and the inner edge

of the convective zone is v = ... = .97 cm/s".

!  Can someone save me researching what inhibits convection inside

this zone?

--rwg