Solar Physics

, Volume 212, Issue 1, pp 3-6

First online:

On the time scale of energy transport in the sun

  • Michael StixAffiliated withKiepenheuer-Institut für Sonnenphysik

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It is pointed out that the time scale of energy transport in the Sun is the Kelvin–Helmholtz time scale, of order 3×107 years, roughly 100 times longer than the photon-diffusion time estimated by Mitalas and Sills (1992). The difference corresponds to a factor U gas/U rad, the ratio of thermal energy density to radiation energy density. Thus the heat transport, even when mediated by photons, is slowed down by the large heat capacity of the star. A numerical example calculation is presented.