Properties of central stars of planetary nebulae with distances in Gaia
  DR2
  Context. We have compiled a catalogue of central stars of planetary nebulae
(CSPN) with reliable distances and positions obtained from Gaia Data Release 2
(DR2) astrometry. Distances derived from parallaxes allow us to analyse the
galactic distribution and estimate other parameters such as sizes, kinematical
ages, bolometric magnitudes, and luminosities. Aims. Our objective is to
analyse the information regarding distances together with other available
literature data about photometric properties, nebular kinematics, and stellar
effective temperatures to throw new light on this rapid and rather unknown
evolutionary phase. We seek to understand how Gaia distances compare with other
indirect methods commonly used and, in particular, with those derived from
non-local thermodynamic equilibrium (non-LTE) models; how many planetary
nebulae (PNe) populate the Galaxy; and how are they spatially distributed. We
also aim to comprehend their intrinsic luminosities, range of physical sizes of
the nebulae; how to derive the values for their kinematical ages; and whether
those ages are compatible with those derived from evolutionary models. Methods.
We considered all PNe listed in catalogues from different authors and in Hong
Kong/AAO/Strasbourg/H{\alpha}(HASH) database. By X-matching their positions
with Gaia DR2 astrometry we were able to identify 1571 objects in Gaia second
archive, for which we assumed distances calculated upon a Bayesian statistical
approach. From those objects, we selected a sample of PNe with good quality
parallax measurements and distance derivations, we which refer to as our Golden
Astrometry PNe sample (GAPN), and obtained literature values of their apparent
sizes, radial and expansion velocities, visual magnitudes, interstellar
reddening, and effective temperatures.
