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The aims of this Working Group are: • To ensure that scientific symposia on planetary nebulae take place regularly, ideally every 5 years. These symposia would preferably be sponsored by the IAU; • To organize and coordinate the Joint Discussions on the subject at the IAU General Assemblies. These discussions should address topics of interest not only to our Division VI but to other Divisions as well; and • To maintain a Web page with general information about the WG, the activities related to planetary nebulae, and the future meetings and symposia.

Focus Meeting 4 (FM4) on Planetary nebulae as probes of galactic structure and evolution was held as part of the XXIXth IAU General Assembly, Honolulu, Hawaii, USA, in August 2015. We had 11 invited reviews, 21 contributed talks, and ~ 30 posters. Because of page limitations, we have decided to publish only the invited reviews. In what follows, we attempt to summarize what the reader can expect to find in these proceedings.

Using the Subaru telescope and its FOCAS spectrograph in multi-object mode, we have obtained spectra of a selection of bright PNs in two galaxies: the Virgo giant elliptical M 60 (NGC 4649), and the starburst spiral M 82. We report on individual extinctions, as determined from the Balmer decrement, and also on the intensities of [O III] 4959 and 5007 relative to Hβ.

Using new, high signal-to-noise CFHT ESPaDOnS visual spectrograms, and archive IUE and FUSE UV spectrograms, together with state-of-the-art non-LTE hydrodynamical model atmospheres, we have obtained accurate He, C, N, O photospheric abundance determinations in the central stars of NGC 2392, IC 4593, and NGC 6826. We compare with the corresponding nebular abundances, taken from the literature. The central star of NGC 2392 shows high He, N, and very low C, O abundances. We propose that these peculiar abundances must have originated in a common-envelope phase of interaction with a close binary companion. If we assume that the companion is more evolved than the visible central star, this offers a way of solving the old mystery of the discrepant He II Zanstra temperature of NGC 2392.

The Local Group dwarf irregular galaxy IC 10 is the nearest starburst galaxy (at 725 kpc) and presents extended and complex HI kinematics. It is believed that IC 10 is still experiencing an intense and very recent burst of star formation, likely triggered by infalling gas from an extended envelope which is counter-rotating with respect to the galaxy proper rotation. In this contribution we summarize our preliminary results (Gonçalves et al. 2011, in prep.) obtained by performing a kinematic analysis of the PN population of IC 10. Our aim is to explore the kinematic connection of its intermediate to old stellar populations with that obtained from HI observations. Some PNe were found at large galactocentric distances and could therefore represent a trace of past tidal interactions.

From a survey of PNs in NGC 300 we obtain its PNLF. We use it to derive a distance estimate, and briefly discuss the PNLF shape.

We present preliminary photometry of 122 PNs discovered in the elliptical galaxy NGC 821. We build the PN luminosity function (PNLF), which gives a distance modulus m - M = 31.9 $\pm$ 0.3, in good agreement, within the uncertainties, with the SBF distance modulus 31.91 $\pm$ 0.17 obtained by Tonry et al. (2001).