MASS-LOSS FROM CENTRAL STARS OF PLANETARY-NEBULAE .2. NGC-40

We have tried to determine the mass loss rate from the central star of NGC 40 with two methods. By fitting the UV P Cygni profiles of C IV, Si IV and He II, we derive a value of log M less-than-or-equal-to -5 [M. yr-1], assuming solar abundances. The star is a WC type, therefore He and C are likely to be overabundant, making the above value an upper limit. By comparing the He I and He II optical and UV emission lines with grids of models for pure He atmospheres of WR stars, we derive log M almost-equal-to -6 [M. yr -1], and this value could be considered a lower limit. Therefore the mass loss rate can be of this order. The measured values of terminal velocity, temperature and mass loss rate, compared with the radiation pressure driven wind theory, confirm that the nucleus of NGC 40 is extremely massive (1 M.) for a central star of Planetary Nebula.