Astrophysical outflows treated initially as spherically symmetric often show evidence for asymmetry once seen at higher resolution. The preponderance of aspherical and multipolar planetary nebulae (PN) and pre-planetary nebulae (PPN) was evident after many observations from the Hubble Space Telescope. Binary interactions have long been thought to be essential for shaping asymmetric PN/PPN, but how? PPN are the more kinematically demanding of the two, and warrant particular focus. I address how progress from observation and theory suggests two broad classes of accretion driven PPN jets: one for wider binaries (PPN-W) where the companion is outside the outer radius of the giant and accretes via Roche lobe overflow, and the other which occurs in the later stages of CE for close binaries (PPN-C). The physics within these scenarios connects to progress and open questions about the role and origin of magnetic fields in the engines and in astrophysical jets more generally.

PNe are known to be photoionized objects. However they also have low-ionization structures (LIS) with different excitation behavior. We are only now starting to answer why most LIS have lower electron densities than the PN shells hosting them, and whether or not their intense emission in low-ionization lines is the key to their main excitation mechanism. Can LIS line ratios, chemical abundances and kinematics enlight the interplay between the different excitation and formation processes in PNe? Based on the spectra of five PNe with LIS and using new diagnostic diagrams from shock models, we demonstrate that LIS’s main excitation is due to shocks, whereas the other components are mainly photoionized. We propose new diagnostic diagrams involving a few emission lines ([N II], [O III], [S II]) and fshocks/f*, where fshocks and f* are the ionization photon fluxes due to the shocks and to the central star ionizing continuum, respectively.

Most planetary nebulae (PNe) show beautiful, axisymmetric morphologies despite their progenitor stars being essentially spherical. Angular momentum provided by a close binary companion is widely invoked as the main agent that would help eject an axisymmetric nebula, after a brief phase of engulfment of the secondary within the envelope of the Asymptotic Giant Branch (AGB) star, known as a common envelope (CE). The evolution on the AGB would thus be interrupted abruptly, its (still quite) massive envelope fully ejected to form the PN, which should be more massive than a PN coming from the same star were it single. We test this hypothesis by deriving the ionised+molecular masses of a pilot sample of post-CE PNe and comparing them to a regular PNe sample. We find the mass of post-CE PNe to be actually lower, on average, than their regular counterparts, raising some doubts on our understanding of these intriguing objects.

The discrepancy between abundances computed using optical recombination lines (ORLs) and collisionally excited lines (CELs) is a major, unresolved problem with significant implications for the determination of chemical abundances throughout the Universe. In planetary nebulae (PNe), the most common explanation for the discrepancy is that two different gas phases coexist: a hot component with standard metallicity, and a much colder plasma enhanced in heavy elements. This dual nature is not predicted by mass loss theories, and direct observational support for it is still weak. In this work, we present our recent findings that demonstrate that the largest abundance discrepancies are associated with close binary central stars. OSIRIS-GTC tunable filter imaging of the faint O ii ORLs and MUSE-VLT deep 2D spectrophotometry confirm that O ii ORL emission is more centrally concentrated than that of [Oiii] CELs and, therefore, that the abundance discrepancy may be closely linked to binary evolution.

The progress in planetary nebulae (PN) research reported in this symposium is reviewed in the context of our current understanding of the PN phenomenon.

It is widely accepted that binary interactions are responsible for the shaping of planetary nebula. However, these binary interactions and evolutionary channels are poorly understood. Our recent study revealed a newly discovered population of low-luminosity, low-metallicity, likely binaries in the Magellanic Clouds: dusty post-RGB stars. They are likely to have evolved off the RGB via binary interaction. In this paper we present preliminary results of the first radial velocity monitoring of the post-RGB stars in the Small Magellanic Cloud (SMC) and the implications on stellar (binary) evolution. We also investigate their link, if any, to the planetary nebulae systems.

The Hong Kong/AAO/Strasbourg Hα (HASH) planetary nebula database is an online research platform providing free and easy access to the largest and most comprehensive catalogue of known Galactic PNe and a repository of observational data (imaging and spectroscopy) for these and related astronomical objects. The main motivation for creating this system is resolving some of long standing problems in the field e.g. problems with mimics and dubious and/or misidentifications, errors in observational data and consolidation of the widely scattered data-sets. This facility allows researchers quick and easy access to the archived and new observational data and creating and sharing of non-redundant PN samples and catalogues.

Magnetic fields are likely to be an efficient mechanism which can affect evolved intermediate mass stars (i.e. post-AGB stars and planetary nebulae) in different ways such as via the shaping of their envelope. However, observational probes for the presence of those fields are still scarce. I will present a summary of the works, including those from our group, on the detection and measurement of magnetic fields in various evolved objects.

The populations of bright planetary nebulae in the discs of spirals appear to differ in their spectral properties from those in ellipticals and the bulges of spirals. The bright planetary nebulae from the bulge of the Milky Way are entirely compatible with those observed in the discs of spiral galaxies. The similarity might be explained if the bulge of the Milky Way evolved secularly from the disc, in which case the bulge should be regarded as a pseudo-bulge.

We present an overview of the present observational status of unexplained spectral phenomena in the ISM. The possibility of organic molecules and solids as the carrier of the DIB, 217 nm feature, ERE, UIR, and the 21 and 30 μm features is discussed.

Diffuse intracluster light (ICL) has now been observed in nearby and in intermediate redshift clusters. Individual intracluster stars have been detected in the Virgo and Coma clusters and the first color-magnitude diagram and velocity measurements have been obtained. Recent studies show that the ICL contains of the order of 10% and perhaps up to 30% of the stellar mass in the cluster, but in the cores of some dense and rich clusters like Coma, the local ICL fraction can be high as 40%-50%. What can we learn from the ICL about the formation of galaxy clusters and the evolution of cluster galaxies? How and when did the ICL form? What is the connection to the central brightest cluster galaxy? Cosmological N-body and hydrodynamical simulations are beginning to make predictions for the kinematics and origin of the ICL. The ICL traces the evolution of baryonic substructures in dense environments and can thus be used to constrain some aspects of cosmological simulations that are most uncertain, such as the modeling of star formation and the mass distribution of the baryonic component in galaxies.

We present results of the mid-IR spectra decomposition for planetary nebulae and compact H ii regions in our Galaxy and Magellanic Clouds. The striking correlation between the required PAH component with “7.7” μm band shifted to about 7.8 μm and electron densities of the modeled sources allows us to argue that this PAH component may be in fact PAH anions (PAH−).

We present the results of a small mid-infrared imaging survey of planetary nebulae. Of 21 objects observed 19 were resolved. Only in NGC 6210 was there a marked contrast between the dust morphology and the emission line morphology. For all the other objects the dust and the gas must be well mixed even in the faint lobes of bipolar objects such as Fg3, Pe1-7, and NGC 6881.

The study of photoionised gas in planetary nebulae (PNe) has played a major role achieving, over the years, a better understanding of a number of physical processes pertinent to a broader range of fields than just PNe studies, ranging from atomic physics to stellar evolution. Whilst empirical techniques are routinely employed for the analysis of the emission line spectra of such objects, the accurate interpretation of the observational data often requires the solution of the radiative transfer (RT) problem in the nebula, via the application of a photoionisation code. A number of large-scale codes have been developed since the late sixties, using various analytical or statistical techniques mainly under the assumption of spherical symmetry and a few in 3D. These codes have been proved to be powerful and in many cases essential tools, but a clear idea of the underlying physical processes and assumptions is necessary in order to avoid reaching misleading conclusions. The development of the codes has been driven by the observational constraints available, but also compromised by the available computer power. Modern codes are faster and more flexible, with the ultimate goal being the achievement of a description of the observations relying on the smallest number of parameters possible. In this light, recent developments have been focused on the inclusion of new atomic data, the inclusion of a realistic treatment for dust grains mixed in the ionised and photon dominated regions (PDRs) and the expansion of some codes to PDRs with the inclusion of chemical reaction networks. Furthermore the last few years have seen the development of fully 3D photoionisation codes based on the Monte Carlo method. A brief review of the photoionisation codes currently in use is given here, with emphasis on recent developments, including the expansion of the models to the 3D domain, the identification of new observational constraints and how these can be used to extract useful information from realistic models.

As an adjunct to the planetary nebula (PN) search from the AAO/UKST H$\alpha$ survey, a visual search was conducted for new emission nebulae from the SHASSA and VTSS surveys, outside a Galactic latitude of $\mid b\mid$ = 10°. Fifteen new objects were found from SHASSA and three from the available fields of VTSS. With one exception, all objects are $> 5^\prime$ across, as smaller nebulae are confused with large numbers of artifacts and compact emitters on these surveys. All previously known PNe larger than this size in the search area, as well as Hewett 1, PG 0108, and PG 0109 were recovered in this blind search. Candidates were selected as discrete, morphologically symmetric H$\alpha$ enhancements, to differentiate them from the ubiquitous diffuse emission structure of the ISM. These criteria were relaxed for the VTSS survey due to its poorer inherent resolution. Most of the new discoveries are probable Stromgren spheres in the ISM. Some show unusual line ratios (e.g. strong [O III] or [N II] emission) based on slit spectroscopy and WHAM data (see Madsen et al. 2006, this volume), suggesting these are ionised by a hot subdwarf or white dwarf star, and may be possible PNe. Our most interesting discovery is a rare bowshock nebula around a bright, previously unnoticed, nova-like cataclysmic variable.

A programme is currently underway to study the structures and kinematics of planetary nebulae known to contain close-binary central stars. Images and high-resolution spectroscopy are presented of the collimated nebula Abell 63 and the ring-like nebula Sp 1. A spatio-kinematical model shows that Abell 63 has a tube-like structure, which has the same inclination as the orbital plane of the central binary system. Kinematic data reveal that Sp 1 is not a hollow sphere, but a tube-like nebula viewed pole-on.

The local planetary nebula (PN) census is dominated by extremely evolved examples, and until recently, was incomplete. New discoveries from the AAO/UKST H$\alpha$ Survey and SHASSA, have partially remedied this problem. In addition, we find that some currently accepted nearby PNe are in fact Strömgren spheres in the ISM ionised by a hot white dwarf. Distance estimates for a robust sample of calibrating PNe from the literature, plus new distances for a number of highly evolved PNe, have allowed a new H$\alpha$ surface brightness – radius relationship to be devised as a useful distance indicator. It covers $>$6 dex in SB, and while the spread in SB is $\sim$1 dex at a given radius, optically thick (mainly bipolar and bipolar-core) PNe tend to populate the upper bound of the trend, while common-envelope PNe and very high-excitation PNe form a sharp lower boundary. Hence, distances can be estimated for all remaining local PNe, allowing the definition of a relatively complete census of PNe in the solar neighbourhood within 1.0 kpc. This provides a first look at the faint end of the PN luminosity function, and new estimates of the space density, scale height, total number, and birth rate of Galactic PNe.

The assumption of spherical symmetry is not justified for the vast majority of PNe. The interpretation of spatially-resolved observations cannot rely solely on the application of 1D codes, which may yield incorrect abundances determinations resulting in misleading conclusions. The 3D photoionisation code MOCASSIN (Monte CArlo SimulationS of Ionised Nebulae) is designed to remedy these shortcomings. The 3D transfer of both primary and secondary radiation is treated self-consistently without the need of approximations. The code was benchmarked and has been applied to the study of several PNe. The current version includes a fully self-consistent radiative transfer treatment for dust grains mixed within the gas, taking into account the microphysics of dust-gas interactions within the geometry-independent Monte Carlo transfer. The new code provides an excellent tool for the self-consistent analysis of dusty ionised regions showing asymmetries and/or density and chemical inhomogeneities. Work is currently in progress to incorporate the processes that dominate the thermal balance of photo-dissociation regions (PDRs), as well as the formation and destruction processes for all the main molecular species.