Published online by Cambridge University Press: 25 April 2016
The astrophysical literature contains many discussions on exactly which changes in a star’s structure are responsible for the extremely large radii found after core hydrogen exhaustion. Different authors favour different mechanisms. Unfortunately none of the proposals are easily verified nor are they easily disproven. In this paper we examine the suggestion that it is the increased central mass concentration (i.e., the growth of the hydrogen exhausted core) which is the primary agent responsible for envelope growth.