Top: rate of change in ⁴He abundance due to the triple-α (red) and ¹²C(α, γ)¹⁶O (blue) reactions at a density of 1.2 × 10⁶ g cm⁻³ and X(¹²C) = 0.1 dependent on temperature; bottom: crossing temperature T_X above which the depletion due to α-captures exceeds that due to triple-α dependent on initial carbon abundance at a density of 1.2 × 10⁶ g cm⁻³. The reaction rates are taken from the JINA Reaclib Database (Cyburt et al. 2010) based on Xu et al. (2013) for the α-capture and Fynbo et al. (2005) for the triple-α reaction.