SIMBAD references

Northern Galactic planetary nebulae (PNs) are studied to disclose possible correlations between the morphology of the nebulae and the evolution of the central stars (CSs). To this end, we have built the best database available to date, accounting for homogeneity and completeness. We use updated statistical distances and an updated morphological classification scheme, and we calculate Zanstra temperatures for a large sample of PNs. With our study we confirm that round, elliptical, and bipolar PNs have different spatial distributions within the Galaxy, with average absolute distances to the Galactic plane of 0.73, 0.38, and 0.21 kpc, respectively. We also find evidence that the distributions of the CS masses are different across these morphological groups, although we do not find that CSs hosted by bipolar PNs are hotter, on average, than CSs within round and elliptical PNs. Our results are in broad agreement with previous analyses, indicating that round, elliptical, and bipolar PNs evolve from progenitors in different mass ranges and might belong to different stellar populations, as also indicated by the helium and nitrogen abundances of PNs of different morphology.