tokens: We thank Joachim Puls for his advice and for the fastwind comparison models; Rolf Kudritzki for making the optical observations available to us; and Miguel Urbaneja for sharing his original CSPN model runs. We also thank the anonymous referees for helpful comments which improved the paper. This work was supported by the Deutsche Forschungsgemeinschaft (DFG) under grants Pa 477/4-1 and Pa 477/7-1.
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