Turbulent planetary nebulae around [ WC ] – type stars ⋆

Through a high-resolution spectroscopic survey, we analyze the velocity field of 16 planetary nebulae with [WC]or wels-type nuclei in comparison with 8 nebulae having other central star types. We found spectral evidence for finite turbulent velocities in [WC]-type planetary nebulae superimposed on an essentially constant expansion velocity pattern. The nebulae around O-type stars show no evidences for significant turbulence while their expansion velocity is found to increase outwards. Both types of nebulae show the same mean expansion velocity. Our results support the earlier suggestions that nebulae surrounding [WC] central stars are likely related to long-lasting momentum-driven phase bubbles. Turbulence in the nebulae can be either triggered, or enhanced, by stellar wind inhomogeneities that appear ubiquitous in Wolf-Rayet nuclei.