[ rā′dē-ə-tĭv ]
The layer of a star that lies just outside the core, to which radiant energy is transferred from the core in the form of photons. In this layer, photons bounce off other particles, following fairly random paths until they enter the convection zone. Despite the high speed of photons, it can take hundreds of thousands of years for radiant energy in the Sun's radiative zone to escape and enter the convection zone.
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