We review recent results that utilize planetary nebulae (PNe) to constrain galactic dynamical and chemical evolution in different environments. Planetary nebulae have become essential probes in both these aspects of galaxy evolution, and novel observations illustrate their potential. Dynamical evolutionary models need observational constraints, and PNe uniquely probe the environment far from the galactic centers. In chemical evolution, the PN progenitor population spans a broad range of formation epochs; the oldest progenitors of local PNe are contemporary with H II regions in z ∼ 2 star-forming galaxies (SFGs). The future will bring even more possibilities in these fields, especially with the advent of extremely large telescopes.

Planetary nebulae (PNe) are essential tracers of the kinematics of the diffuse halo and intracluster light where stellar spectroscopy is unfeasible, due to their strong emission lines. However, that is not all they can reveal about the underlying stellar population. In recent years, it has also been found that PNe in the metal-poor halos of galaxies have different properties (specific frequency, luminosity function), than PNe in the more metal-rich galaxy centers. A more quantitative understanding of the role of age and metallicity in these relations would turn PNe into valuable stellar-population tracers. In order to do that, a full characterization of PNe in regions where the stellar light can also be analysed in detail is necessary. In this work, we make use of integral-field spectroscopic data covering the central regions of galaxies, which allow us to measure both stellar ages and metallicities as well as to detect PNe. This analysis is fundamental to calibrate PNe as stellar population tracers and to push our understanding of galaxy properties at unprecedented galactocentric distances.

We summarize the main results from the survey of Planetary Nebulae (PNe) in M 31 with Megacam@CFHT and subsequent spectroscopy with Hectospec@MMT. We identified ∼5000 PNe in M 31 (∼1200 with spectroscopy; ∼200 with chemical abundances). We find a PN Luminosity Function faint-end rise, linked to a percentage of older stars in the parent population. We utilize PN extinction to distinguish young and old PNe. We find that the [Ar/H] vs [O/Ar] plane for emission-line nebulae is analogous to the [Fe/H] vs [α/Fe] plane for stars, and exploration of the M 31 disc PNe in this plane allowed us to constrain its chemical enrichment history. We find the kinematically and chemically distinct thin and thick discs of M 31, and that the G1-clump substructure is formed from perturbed disc material. We infer that M 31 has had a wet major (mass-ratio∼1:5) merger ∼2.5-4 Gyr ago, and obtain important constraints on the cannibalized satellite properties.

We compare different estimates of distances to planetary nebulae (PNe), namely, Gaia parallaxes and statistical values, in order to determine the most reliable distance for each PN. In numerous instances, we find that the distances derived from the Gaia parallaxes are not the most reliable, and that better estimates can be obtained from the median of the available statistical values. Our resulting distances imply that the distributions of distances from the Galactic plane of PNe with [WR] central stars is different from the distributions of both non-[WR] hydrogen-poor central stars and hydrogen-rich central stars.

We report spectroscopic surveys of planetary nebulae (PNe) in the Milky Way and Andromeda (M31), using the 10.4-m Gran Telescopio Canarias (GTC). The spectra are of high quality and cover the whole optical range, mostly from 3650 Å to beyond 1 μm, enabling detection of nebular emission lines critical for spectral analysis and photoionization modeling. We obtained GTC spectra of 24 compact (angular diameter <5 arcsec) PNe located in the Galactic disk, ∼3–20 kpc from the Galactic centre, and that can be used to constrain stellar evolution models and derive radial abundance gradients of the Milky Way. We have observed 30 PNe in the outer halo of M31 using the GTC. These halo PNe are uniformly metal-rich and probably all evolved from low-mass stars, consistent with the conjecture that they formed from the metal-rich gas in M31 disk but were displaced to their present locations due to galaxy interactions.

The Planetary Nebula Luminosity Function (PNLF) remains an important extragalactic distance indicator despite a still limited understanding of its most important feature - the bright cut-off. External galaxies benefit from consistent distance and extinction, which makes determining the PNLF easier but detailed study of individual objects much more difficult. Now, the advent of parallaxes from the Gaia mission has dramatically improved distance estimates to planetary nebulae (PNe) in the Milky Way. We have acquired ground-based narrowband imagery and measured the [OIII] fluxes for a volume-limited sample of hundreds of PNe whose best distance estimates from Gaia parallaxes and statistical methods place them within 3 kpc of the Sun. We present the first results of our study, comparing the local PNLF to other galaxies with different formation histories, and discussing how the brightness of the PNe relates to the evolutionary state of their central stars and the properties of the nebula.

A quarter of a century has passed since the observing technique of integral field spectroscopy (IFS) was first applied to planetary nebulae (PNe). Progress after the early experiments was relatively slow, mainly because of the limited field-of-view (FoV) of first generation instruments. With the advent of MUSE at the ESO Very Large Telescope, this situation has changed. MUSE is a wide field-of-view, high angular resolution, one-octave spanning optical integral field spectrograph with high throughput. Its major science mission has enabled an unprecedented sensitive search for Lyα emitting galaxies at redshift up to z=6.5. This unique property can be utilized for faint objects at low redshift as well. It has been demonstrated that MUSE is an ideal instrument to detect and measure extragalactic PNe with high photometric accuracy down to very faint magnitudes out to distances of 30 Mpc, even within high surface brightness regions of their host galaxies. When coupled with a differential emission line filtering (DELF) technique, MUSE becomes far superior to conventional narrow-band imaging, and therefore MUSE is ideal for accurate Planetary Nebula Luminosity Function (PNLF) distance determinations. MUSE enables the PNLF to become a competitive tool for an independent measure of the Hubble constant, and stellar population studies of the host galaxies that present a sufficiently large number of PNe.

The Multi-Unit Spectroscopic Explorer (MUSE) has enabled a renaissance of the planetary nebula luminosity function (PNLF) as a standard candle. In the case of NGC 300, we learned that the precise spectrophotometry of MUSE was crucial to obtain an accurate PNLF distance. We present the advantage of the integral field spectrograph compared to the slit spectrograph in delivering precise spectrophotometry by simulating a slit observation on integral field spectroscopy data. We also discuss the possible systematic shift in measuring the PNLF distance using the least-square method, especially when the PNLF cutoff is affected by small number statistics.

Even after decades of usage as an extragalactic standard candle, the universal bright end of the planetary nebula luminosity function (PNLF) still lacks a solid theoretical explanation. Until now, models have modeled planetary nebulae (PNe) from artificial stellar populations, without an underlying cosmological star formation history. We present PICS (PNe In Cosmological Simulations), a novel method of modeling PNe in cosmological simulations, through which PN populations for the first time naturally occur within galaxies of diverse evolutionary pathways. We find that only by using realistic stellar populations and their metallicities is it possible to reproduce the bright end of the PNLF for all galaxy types. In particular, the dependence of stellar lifetimes on metallicity has to be accounted for to produce bright PNe in metal-rich populations. Finally, PICS reproduces the statistically complete part of the PNLF observed around the Sun, down to six orders of magnitude below the bright end.

We analyzed VLT/MUSE data for 20 galaxies in the ESO public archive to identify their systems’ planetary nebulae (PNe). Using the differential emission line filter (DELF) technique, we performed photometry of the galaxies’ PNe and determined their distances via the planetary nebula luminosity function (PNLF). Of the 16 galaxies for which a quality PNLF could be formed, two are isolated and more distant than 30 Mpc and therefore, relatively unaffected by Hubble Flow peculiar velocities. Using these data, we derived a Hubble Constant of 74.2 ± 7.2 (stat) ±3.7 (sys) km s−1 Mpc−1, a value that is similar to that found from other quality indicators (e.g., Cepheids, the tip of the red giant branch, and surface brightness fluctuations), but with a larger uncertainty due to the small number of galaxies. We describe how to improve PNLF measurements so that the precision of the technique is comparable to that of other quality distance indicators. We also describe a path forward in the era of ELTs that supersedes current techniques.

Thanks to its characteristic bright cut-off, the planetary nebulae luminosity function (PNLF) has now become a well-established extragalactic distance indicator that is in principle applicable to all types of galaxies. Most recently, several studies have demonstrated how the use of integral-field spectroscopy can lead to even more precise PNLF measurements, in particular as it allows to probe the central regions of galaxies and obtain well-sampled PNLF distributions. In this respect, adaptive optics (AO) is expected to further increase the scope and reach of PNLF measurements, as it should allow for the detection of even more and more distant PNe. This proceeding presents first results of the investigation of the MUSE-AO performance in relation to the detection of PNe in external galaxies, based on all galaxies with wide-field mode AO observations in the ESO archive.

Nearly all intragroup (IGL) and intracluster light (ICL) comes from stars that are not bound to any single galaxy but were formed in galaxies and later unbound from them. Kinematic information on these very low surface brightness structures mostly comes from discrete tracers such as planetary nebulae and globular clusters, showing highly unrelaxed velocity distributions. Cosmological hydrodynamical simulations provide key predictions for the dynamical state of IGL and ICL and find that most IC stars are dissolved from galaxies that subsequently merge with the central galaxy. The increase of the measured velocity dispersion with radius in the outer halos of bright galaxies is a key feature to identify IGL and ICL components. In the local groups and clusters, IGL and ICL are more centrally concentrated than the galaxies, with their typical fractions that are few to ten percent, i.e. significantly lower than the average values in more evolved clusters. The properties of ICPNe, their luminosity functions and specific frequencies were key to further constraint the age (10 Gyr) and the metallicity ([M / Fe]< −1.0) of the IC/IGL. The results in the nearby clusters are briefly illustrated.

Gaia astrometry was used to explore the properties of Galactic Post-AGB stars in the literature. DR3 precise parallaxes allowed us to isolate a small group of stars in the direction of the Large Magellanic Cloud (LMC) previously reported as post-AGB stars in the LMC, but that, according to their distances, seem to be located in an intermediate region between the LMC and the Galaxy. In order to verify this, we have used a classifier that allows us to evaluate the probability of a star belonging to the Milky Way (MW) or the LMC. This classifier is based on an Artificial Neural Network (ANN) algorithm and is fed with the astrometry and photometry published in DR3. In this presentation, we study the membership probabilities of several samples of stars in the direction of the LMC. As a result, we have obtained that around 25-30% of stars in our samples, suspected to belong to the LMC, have indeed low probabilities of belonging to either one galaxy or the other. On the contrary, they seem to be located in an intermediate region between the two galaxies. We also analysed the radial velocity distributions of the different samples and the location of the stars in a colour-magnitude diagram. APOGEE data was also used to study the chemical abundances of stars in the different regions (LMC, MW, and intermediate population).

We have undertaken a deep investigation of a well defined sample of 136 PNe located in a 10×10 degree central region of the Galactic Bulge observed with the ESO VLT and supplemented by archival HST images. These studies have provided precise morphologies, major axes position angles and the most robust sample of consistently derived chemical abundances available to date. Using these data we have statistically confirmed, at 5σ, the precise PNe population that provides the PNe alignment of major axes previously suggested in the Galactic Bulge, revealed a partial solution to the sulfur anomaly and uncovered interesting morphological, abundance and kinematic features. We summarise the most significant findings here with detailed results appearing in a series of related publications.

Planetary nebulae (PNe) are excellent tracers of the metal-poor haloes of nearby early-type galaxies. They are commonly used to trace spatial distribution and kinematics of the halo and intracluster light at distances of up to 100 Mpcs. The results on the early-type galaxy M105 in the Leo I group represent a benchmark for the quantitative analysis of halo and intragroup light. Since the Leo I group lies at just a 10 Mpc distance, it is at the ideal location to compare results from resolved stellar populations with the homogeneous constraints over a much larger field of view from the PN populations. In M105, we have – for the first time – established a direct link between the presence of a metal-poor halo as traced by resolved red-giant branch stars and a PN population with a high specific frequency (α-parameter). This confirms our inferences that the high α-parameter PN population in the outer halo of M49 in the Virgo Cluster traces the metal-poor halo and intra-group light.

We present literature on abundance determinations in planetary nebulae (PN) as well as public tools that can be used to derive them. Concerning direct methods to derive abundances we discuss in some depth such issues as reddening correction, use of proper densities and temperatures to compute the abundances, correction for unseen ionic stages, effect of stellar absorption on nebular spectra, and error analysis. Concerning photoionization model-fitting, we discuss the necessary ingredients of model stellar atmospheres, the problem of incomplete slit covering and the determination of the goodness of fit. A note on the use of IFU observations is given. The still unsolved problem of temperature fluctuations is briefly presented, with references to more detailed papers. The problem of abundance discrepancies is touched upon with reference to more extensive discussions in the present volume. Finally carbon footprint issues are mentioned in the context of extensive PN modeling and large databases.

We present spectroscopy of NGC 3242, NGC 6153, and NGC 7009 at very high spectral resolution (λ / δλ = 75, 000 – 100, 000) obtained with the Manchester Echelle Spectrograph at the 2.1m telescope of the Observatorio Astronómico Nacional on the Sierra San Pedro Mártir. We study the kinematics of the plasma within the nebular shells, decomposing the observed line profiles considering the microscopic, macroscopic, and observational processes that broaden them. The residual kinematic structure, defined as the sum of velocity gradients, kinematic structure, and seeing dominates the broadening of the lines of heavy elements. We estimate the effect of velocity gradients, finding that it can account only for a minority of this residual kinematic structure. Whatever the origin of this residual kinematic structure, it is an important component of the kinematics of the ionized plasma within the nebular shell and implies an important energy source that is not contemplated in photoionization models of planetary nebulae.

Extinction correction is the quintessence of astronomy. To achieve precision astrophysics in plasma diagnostics as in the theme of the present Proceedings, one must perform extinction correction properly before executing any line diagnostics of line-emitting objects including planetary nebulae. By making use of the inseparable relationship between extinction correction and plasma diagnostics, we establish a novel method to determine the physical conditions of a line-emitting target and the extinction characteristics along the line of sight toward the target simultaneously and self-consistently. This approach is made possible by the exact analytical expressions for the extinction parameters in terms of the emission properties of the target and by statistical optimization of the extinction parameters to find the robust physical conditions of the target.

Abundance determinations in planetary nebulae (PNe) are crucial for understanding stellar evolution and the chemical evolution of the host galaxy.

We discuss the complications involved when the presence of a metal-rich phase is suspected in the nebula. We demonstrate that the presence of a cold region emitting mainly metal recombination lines necessitates a detailed treatment to obtain an accurate assessment of the enrichment of this cold gas phase.

More than three decades after the pioneering imaging catalog by Balick (1987), where the small-scale and low-ionization structures (LISs) in planetary nebulae (PNe) became evident, the present study conducts a comprehensive statistical analysis of LISs’ physical-chemical and excitation properties. Gathering the largest dataset to date, we compare LISs with high-ionization components (rims/shells) across a diverse sample of PNe. Key findings include lower electron densities (NeS ii) in LISs than in adjacent rims/shells and comparable electron temperatures (Te N ii and O iii) between these two nebular componets. Various optical diagnostic diagrams, while revealing a clear excitation stratification between these groups of components, are not good enough to clearly pinpoint the main excitation mechanism behind the LISs line-emission. Photoionization and shock models highlight a notable overlap between mechanisms, emphasizing the coexistence of both excitation processes. Contrary to expectations, shocks are unlikely to be the primary excitation source for most of LISs in PNe.