Dependence [C/O] vs. [Fe/H]. The SWP are shown with red circles. Larger circles indicate the stars of larger masses. Error bars from the determinations of the mean [C/O] in the samples of SWP and non-SWP are shown by the red and blue arrows. Linear approximation results for the SWP and non-SWP stars shown by red ([C/O] = ((−0.576 ± 0.273) ⋅ [Fe∕H] + 0.047 ± 0.0158) and blue ([C/O] = (0.759 ± 0.077) ⋅ [Fe∕H] + 0.0079 ± 0.006) lines, respectively.