\label{fig:hrd} HR-Diagram showing a \(1.5{{{}{{{}{\mathrm{M}}}_\odot}}}\) MESA calculations. The black symbols show the locations of different evolutionary points (EPs) discussed in the text. The zero age main sequence (ZAMS) is determined when the H-burning luminosity equals the stellar luminosity. The end of the main sequence (TAMS) is chosen as the point where core hydrogen mass fraction decreases below \(1\%\). The red giant branch EP (RGB) is chosen as the location of the model that better reproduces the observed large and small separation for \({\rm{KIC}8366239}\). The luminosity bump (BUMP) marks the location on the red giant branch where the outward moving H-shell reaches regions previously occupied by the receding convective envelope. The tip of the red giant (TIP) is determined by the maximum luminosity of purely H-shell burning models. Stars doing stable core-He burning are selected when only \(1\%\) of He is left in their cores (CLUMP). Finally the WD cooling sequence is determined when the stellar luminosity reaches \(10^{-2} {{{}{{{}{\mathrm{L}}}_{\odot}}}}\).