ON THE DISTANCE TO GALACTIC PLANETARY-NEBULAE

The distances are determined for 145 Galactic planetary nebulae, using two methods. The distances for a sample of 131 planetary nebulae are determined using method A, based on the stellar mass and surface gravity. Method B, making use of the stellar luminosity, is applied to another sample of 61 planetary nebulae, of which 47 are in common with those in the sample for method A. The properties of the central star, such as the core mass, luminosity, and surface gravity, are inferred from the modeling of the distance-independent parameters. The results from the two methods used in this paper are consistent with each other. A distance of 11.3 kpc is found for K648 using method A of this work. This is in good agreement with the distance of 10 kpc of its hosting globular cluster M15. The distances obtained in this work are found in between the ''long'' distance scales, such as the spectroscopic distance of Mendez et al., the statistical distances of Cudworth, Kingsburgh & Barlow, and Kingsburgh & English, and the ''short'' distance scales, such as the ''standard distances'' of Gathier, the mean reddening distance of Pottasch, the statistical distances of Acker, Maciel & Pottasch, and Daub. On average, the newly recalibrated distances of Cahn et al. show only 2% differences from the method A distances in this work, with a standard deviation of about 75%. The Mendez, Kudritzki, & Herrero spectroscopic distances show the best correlation with the distances of this work.