Evolution of [C/H] in CEMP-s star models of different initial and accreted masses (given in solar masses in the top right corner of each panel) with rotational mixing, gravitational settling, and thermohaline mixing. The three sets of lines correspond to different AGB donor masses (marked on the left). The colour intensity indicates the specific angular momentum of accreted material. From brightest to darkest, the lines correspond to j_a = 0 (no rotation), 0.02,0.04,0.2,0.7,2.0 (× 10¹⁷ cm²s^-1). The corresponding rotation velocities are listed in the bottom right corner of each panel (to reduce crowding not all j_a cases are shown in every panel). The solid part of each line delimits ages between 10 and 13.8 Gyr (for panel a computations were stopped at t = 16 Gyr). The points are CEMP stars ([C/Fe] ≥ 0.9; Masseron et al. 2010) from SDSS with − 2.5 ≤ [Fe/H] ≤ −2.0 (Lee et al. 2013).