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We analyze the chemical composition of the central star of the planetarynebula NGC 6543 based upon a detailed NLTE model of its stellar wind. Thelogarithmic abundances by number are H=12.00, He=11.00, C=9.03, N=8.36, O=9.02,Si=8.19, P=5.53, S=7.57 and Fe=7.24. Compared with the solar abundances, mostof the elements have solar composition with respect to hydrogen except C whichis overabundant by 0.28 dex and Fe which is depleted by $\sim 0.2$ dex.Contrary to most previous work, we find that the star is not H-poor and has anormal He composition. These abundances are compared with those found in thediffuse X-ray plasma and the nebular gas. Compared to the plasma emitting indiffuse X-rays, the stellar wind is much less depleted in iron. Since the irondepletions in the nebular gas and X-ray plasma are similar, we conclude thatthe plasma emitting diffuse X-rays is derived from the nebular gas rather thanthe stellar wind. Excellent agreement is obtained between the abundances in thestellar wind and the nebular recombination line abundances for He, C, and Orelative to H. On the other hand, the derived stellar N abundance is smallerthan the nebular N abundance derived from recombination lines and agrees withthe abundance found from collisionally-excited lines. The mean temperaturevariation determined by five different methods indicates that the difference inthe nebular abundances between the recombination lines and collisionallyexcited lines can be explained as due to the temperature variations in achemically homogeneous medium.

NLTE Model of NGC 6543's Central Star and its Relation with the Surrounding Planetary Nebula