Hertzsprung–Russel diagram of the tertiary star in ξ Tau. The evolution of the ZAMS star starts at the lower-left corner, and the star evolves through a series of evolutionary phases until it reaches RLOF near the tip of the AGB (indicated with a bullet). During the RLOF phase the star loses mass in episodes which causes the evolution to be quenched, as indicated in the track to the bottom right after the bullet point.