We present a detailed analysis of the planetary nebula M4–18 ( G146.7+07.6 ) and its WC10-type Wolf-Rayet central star , based on high quality optical spectroscopy ( WHT/UES , INT/IDS , WIYN/DensPak ) and imaging ( HST/WFPC2 ) .
From a non-LTE model atmosphere analysis of the stellar spectrum , we derive T _ { eff } =31 kK , log ( \dot { M } / M _ { \odot } yr ^ { -1 } ) =–6.05 , v _ { \infty } =160 km s ^ { -1 } and abundance number ratios of H/He < 0.5 , C/He=0.60 and O/He=0.10 .
These parameters are remarkably similar to He 2–113 ( [ WC10 ] ) .
Assuming an identical stellar mass to that determined by De Marco et al .
for He 2–113 , we obtain a distance of 6.8 kpc to M4–18 ( E _ { B - V } =0.55 mag from nebular and stellar techniques ) .
This implies that the planetary nebula of M4–18 has a dynamical age of \sim 3 100 years , in contrast to \geq 270 years for He 2–113 .
This is supported by the much higher electron density of the latter .
These observations may only be reconciled with evolutionary predictions if [ WC ] -type stars exhibit a range in stellar masses .

Photo-ionization modelling of M4–18 is carried out using our stellar WR flux distribution , together with blackbody and Kurucz energy distributions obtained from Zanstra analyses .
We conclude that the ionizing energy distribution from the Wolf-Rayet model provides the best consistency with the observed nebular properties , although discrepancies remain .