Meeting number 384 in the IAU’s Symposium series, Planetary Nebulae: a Universal Toolbox in the Era of Precision Astrophysics, featured an overwhelming array of exciting observational and theoretical developments in the study of planetary nebulae. I attempt to identify the themes and threads that ran through the meeting, some of them popping up in unexpected ways and connecting otherwise disparate science sessions. I also highlight key open questions that this meeting has raised for the benefit of future planetary nebula research.

We calculated the positions and velocities of 47 dwarf galaxies using a Bayesian approach. Their angular momentum distribution shows that between 36% and 57% of the dwarf galaxies are located in the Vast Polar Structure (VPOS), which could conflict with expectations for a cosmological infall of primordial dwarfs. Using four gravitational potential models with mass spans from 2.8 × 1011 M⊙ to 15 × 1011 M⊙, we find that dwarf galaxies are over-concentrated near their pericenters compared to what Kepler’s law would expect. This suggests that there may be a large number of dwarf galaxies that have not yet been discovered, or that they are not satellites of the Milky Way.

We have introduced a quantitative and automated method to parameterize star clusters in the Magellanic Clouds (MCs) using the Gaia DR3 data. We used the existing cluster catalogs and extracted their Gaia DR3 data and nearby field regions. We automated the Field Star Decontamination (FSD) algorithm with multiple annular field regions for isolated clusters. We estimated the LMC and SMC clusters’ age, extinction, distance modulus, and metallicity using a Bayesian approach. We expect to parameterize many clusters in the outer LMC with the help of the wide coverage of the Gaia data. We aim to identify correlated cluster formation episodes between the MCs, thereby throwing light on their interaction history. Here we present the preliminary results of this study.

Andromeda (M 31) is the nearest giant spiral galaxy to our Milky Way, and, over the past few decades, has been dubbed the most massive member of the Local Group. I explore the evolution of the measured mass of M 31 over the past ∼80 years, reviewing the different observational and modelling techniques that have developed over time to measure its mass. I discuss the best present-day constraints of the mass of M 31 and the consistency of different techniques.

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.

The magnetic network is a typical magnetic structure of the quiet Sun. Investigating its cycle dependence is crucial for understanding its evolution. We aim to identify and analyze the spatial scales of the magnetic network within magnetic power spectra derived from high-resolution Solar and Heliospheric Observatory (SOHO)/Michelson Doppler Imager (MDI) and Solar Dynamics Observatory (SDO)/ Helioseismic and Magnetic Imager (HMI) synoptic magnetograms. The data sets cover the entirety of solar cycles 23, 24, and part of cycle 25. We find that the identified magnetic network sizes identified range from 26 Mm to 41 Mm. There seems to be no obvious dependence on the solar cycle, and the sizes are distributed uniformly within the identification range.

We present new high-spectral resolution échelle spectra of IC 4997 obtained in 2023 June to study the evolution of its recently reported variable Hα emission line profile. Compared with similar spectra from 2020 September, the new ones also show a single-peaked profile but the full velocity width of the Hα wings has increased by a factor of; 1.2. Besides, we use our high-resolution échelle spectra to investigate the internal kinematics of the nebula. Preliminary analysis suggests that the two shells of IC 4997 are kinematically resolved: the outer shell expands at; 10–14 km s-1 and the inner shell at; 25 km s-1.

Prolate rotation is characterized by a significant stellar rotation around a galaxy’s major axis, which contrasts with the more common oblate rotation. Prolate rotation is thought to be due to major mergers and thus studies of prolate-rotating systems can help us better understand the hierarchical process of galaxy evolution. Dynamical studies of such galaxies are important to find their gravitational potential profile, total mass, and dark matter fraction. Recently, it has been shown in a cosmological simulation that it is possible to form a prolate-rotating dwarf galaxy following a dwarf-dwarf merger event. The simulation also shows that the unusual prolate rotation can be time enduring. In this particular example, the galaxy continued to rotate around its major axis for at least 7.4 Gyr (from the merger event until the end of the simulation). In this project, we use mock observations of the hydro-dynamically simulated prolate-rotating dwarf galaxy to fit various stages of its evolution with Jeans dynamical models. The Jeans models successfully fit the early oblate state before the major merger event, and also the late prolate stages of the simulated galaxy, recovering its mass distribution, velocity dispersion, and rotation profile. We also ran a prolate-rotating N-body simulation with similar properties to the cosmologically simulated galaxy, which gradually loses its angular momentum on a short time scale ∼ 100 Myr. More tests are needed to understand why prolate rotation is time enduring in the cosmological simulation, but not in a simple N-body simulation.

Despite model predictions, many planetary nebulae appear to have a relatively rich molecular content. Observational studies of over 30 such objects show the presence of a variety of gas-phase molecules, from simple species such as CN and CS, to more complex organics including H2CO, HC3N, c-C3H2, and CH3CN. Other PNe contain fullerenes; carbonaceous and silicate dust features are also found. Molecular abundances also do not appear to vary with nebular age. Remnant material from the asymptotic giant branch appears to undergo chemical processing in the protoplanetary nebula phase and then is frozen out in planetary nebulae. PN ejecta are thus in part molecular in content and may account for the observation of complex molecules in diffuse clouds.

I review methods and techniques to build mass models of disk galaxies from gas dynamics. I focus on two key steps: (1) the derivation of rotation curves using 3D emission-line datacubes from H I, CO, and/or Hαobservations, and (2) the calculation of the gravitational field from near-infrared images and emission-line maps, tracing the stellar and gas mass distributions, respectively. Mass models of nearby galaxies led to the establishment of the radial acceleration relation (RAR): the observed centripetal acceleration from rotation curves closely correlates with that predicted from the baryonic distribution at each galaxy radius, even when dark matter supposedly dominates the gravitational field. I conclude by discussing the (uncertain) location of Local Group dwarf spheroidal galaxies on the RAR defined by more massive disk galaxies.

Using hydrodynamic simulations and photoionization calculations, we demonstrate that quasar emission line spectra contain information on the driving mechanism of galaxy-scale outflows. Outflows driven by a hot shocked bubble are expected to exhibit LINER-like optical line ratios, while outflows driven by radiation pressure are expected to exhibit Seyfert-like line ratios. Driving by radiation pressure also has a distinct signature in the narrow UV lines, which is detected in an HST-COS spectrum of a nearby quasar hosting a large-scale wind.

The recent acquisition of high-quality deep images of planetary nebulae (PNe) in world-class telescopes has allowed the detection for the first time of a wealth of small-scale morphological features and structures that highlight the complexity of their formation history and the physical processes modeling them. In this work we present the discovery of a series of clumps embedded within the ionized nebular shell of the evolved PN NGC 3587, the Owl Nebula, that had escaped previous detections. The multi-wavelength analysis provided by GEMINI, NOT and Aristarchos in the optical and CFHT and Spitzer infrared images indicates that these clumps are formed by denser and colder material, with a notable content of molecular H2.

Bipolar or multipolar lobes in pre-planetary nebulae (pPNe) often exhibit intertwined outer whorled patterns, resulting from stellar wind matter accumulation during the asymptotic giant branch (AGB) phase. These structures are likely triggered by stellar or substellar companions. We regard that CW Leonis currently stands at a critical transition moment, providing a vivid illustration of the progression from an AGB star in a binary system to a pPN. We have found that CW Leonis has shown significant enhancements in its optical and near-infrared light curves over the past two decades, with the recent Hubble Space Telescope image finally revealing the long-awaited central star. Utilizing an eccentric-orbit binary model, we can reproduce the position-angle dependence of the expansion velocity in the whorled pattern around CW Leonis, suggesting a nearly face-on orbital inclination. Its contradiction to the features in the innermost circumstellar envelope, corresponding to a nearly edge-on inclination, may imply the presence of an additional companion. Our updated theoretical framework explores the complexity of the whorled pattern. Further identifying and monitoring phase-transition candidates at the tip of the AGB will provide valuable insights into the AGB-pPN transition and the role of companions in shaping the morphological evolution of these stellar objects.

During minima of solar activity, it is possible to estimate the influence of convection zone turbulence on the magnetic flux tubes forming active regions (ARs), because the toroidal field of the old cycle weakens, and the new toroidal field is still weak. We analyzed ARs of solar minima between 23-24 and 24-25 solar cycles. ARs were classified as regular, irregular and unipolar spots. Regular ARs follow the empirical laws consistent with the Babcock–Leighton dynamo theory. We found that regular ARs dominate by flux and by number during the solar minima. Irregular ARs are mainly represented by bipolar structures of deformed orientation and contribute only one-third in the total flux and one-third in the total number. Very complex multipolar ARs are extremely rare. So, during solar minima the global dynamo still guides the formation of ARs, whereas the turbulence only slightly affects the toroidal flux tubes orientation.

Solar activity shows an 11-year (quasi)periodicity with a pronounced, but limited variability of the cycle amplitudes. The properties of active region (AR) emergence play an important role in the modulation of solar cycles and are our central concern in building a model for predicting future cycle(s) in the framework of the Babcock–Leighton (BL)-type dynamo. The emergence of ARs has the property that strong cycles tend to have higher mean latitudes and lower tilt angle coefficients. Their non-linear feedbacks on the solar cycle are referred to as latitudinal quenching and tilt quenching, respectively. Meanwhile, the stochastic properties of AR emergence, e.g., rogue ARs, limit the scope of the solar cycle prediction. For physics-based prediction models of the solar cycle, we suggest that uncertainties in both the observed magnetograms assimilated as the initial field and the properties of the AR emergence should be taken into account.

Understanding the origin of the stellar streams around the Milky Way can be of great relevance to learn about the history of the Milky Way and the formation of its substructures. A previous study on the Milky Way streams (Pawlowski et al. 2012) showed that many of these (7 out of 14) present a similar orientation to that of the disk of satellite galaxies (DoS) and the young globular clusters of the Milky Way. This suggests that the DoS, the young globular clusters and a large fraction of the Milky Way streams have a correlated origin. The authors proposed that these substructures could have formed as a result of a past interaction between the Milky Way and the Andromeda galaxy. In this work, we revise the distribution of the orbital poles of the Milky Way streams in light of the latest stream dataset, which includes a total of 97 streams.

As AGB stars evolve to planetary nebulae (PNe), the geometry of the ejected mass transforms from nearly spherical to extremely aspherical. The mechanisms governing this transformation are plausibly linked to binarity and the associated production of disks and jets during the transitional (post-AGB) evolutionary stage. We are carrying out an ALMA survey of a representative sample of bipolar/multipolar post-AGB objects to obtain high angular-resolution (0″.11) observations of the CO(3–2) and 6–5 emission and study the collimated outflows and central disks. We present highlights from our ongoing survey – e.g., the presence of bipolar or multipolar high-velocity outflows, dense toroidal waists, and in one case, a circular ring around the central bipolar nebula. We will use radiative transfer modeling to derive accurate outflow momenta, masses, and mass-loss rates for our sample, thereby constraining different classes of binary PN-shaping models.

We study the m = 1 high-latitude inertial mode and its contribution to the latitudinal transport of the Sun’s angular momentum. Ring-diagram helioseismology applied to 5° tiles is used to obtain the horizontal flows near the surface of the Sun. Using 10 years of data from SDO/HMI, we report on the horizontal eigenfunction and Reynolds stress $\[{Q_{\theta \phi }} = \langle {u'_\theta }{u'_\phi }\rangle \]$ for the m = 1 high-latitude inertial mode (frequency –86.3 nHz, critical latitudes ±58°). We find that Qθφ takes significant values above the critical latitude and is positive (negative) in the northern (southern) hemisphere, implying equatorward transport of angular momentum. The Qθφ peaks above latitude 70° with a value of 38 m2/s2.

We used the OGLE data to search for binary central stars of planetary nebulae (CSPNe) in the Large Magellanic Cloud (LMC). Nine binary CSPNe with periods between 0.24 and 23.6 days were discovered. The obtained fraction of binary CSPNe for the LMC PNe is without correcting for incompleteness.