I summarize the scenario by Goudfrooij (2018) in which the bulk of the ultraviolet (UV) upturn of giant early-type galaxies (ETGs) is due to helium-rich stellar populations that formed in massive metal-rich globular clusters (GCs) and subsequently dissolved in the strong tidal field in the central regions of the massive host galaxy. These massive GCs are assumed to show UV upturns similar to those observed recently in M87, the central galaxy in the Virgo cluster of galaxies. Data taken from the literature reveals a strong correlation between the strength of the UV upturn and the specific frequency of metal-rich GCs in ETGs. Adopting a Schechter function parametrization of GC mass functions, simulations of long-term dynamical evolution of GC systems show that this correlation can be explained by variations in the characteristic truncation mass Mc such that Mc increases with ETG luminosity in a way that is consistent with observed GC luminosity functions in ETGs. These findings suggest that the nature of the UV upturn in ETGs and the variation of its strength among ETGs are causally related to that of helium-rich populations in massive GCs, rather than intrinsic properties of field stars in ETGs.

A few Be X-ray binaries might constitute a group of special sources because the neutron stars in them may have superstrong magnetic fields. Generally, the neutron stars have long spin periods and some emission lines are shown from the B type star, which is attributed to an equatorial disc. We re-build new dimensionless torque models and obtain the superstrong magnetic fields of the neutron stars in the Be X-ray binaries in Large Magellanic Cloud, Small Magellanic Cloud and Milky Way when the compressed magnetosphere is considered. Although our conclusions are obtained when the disk accretion mode is considered, the results may be applied the Be X-ray binaries with wind accretion mode. SXP1323 and 4U 2206+54, in which the magnetic fields of the NSs may be close to the maximum ‘virial’ value, are the best objects to explore superstrong magnetic field.

The populations of planetary nebulae (PNe) probe metallicity and chemical content (and its evolution) of the parent galaxy, giving clues to galaxy formation and evolution. This sub-field of extra-galactic PN research has been particularly active in the recent years. Comparison of data and models yielded estimates of global cosmic enrichment and provided constraints to galaxy formation history. In external spiral galaxies, the chemical contents of PNe and H II regions can be compared to disclose possible evolution of the radial metallicity gradient, which is, in turn, a powerful constraint to galactic chemical evolutionary models. In the Milky Way, recent PN progenitor dating and new chemical abundances offer an updated look into our own Galaxy. Collectively, Galactic and extra-galactic radial metallicity gradients from emission-line probes (PNe and H II regions) can be compared to have a cosmological outlook on galactic evolution.

Radio jets are the large-scale and extragalactic footprints of accretion onto supermassive black holes, and are suggested to be the key ingredient controlling the galaxy stellar mass function. Of particular importance is their jet power - the time-averaged energetic feedback into their environment. Hence, the dynamics, energetics and life-cycles of radio-loud AGN (RLAGN) must be understood in order to build a qualitative and quantitative picture of their impact over cosmic time. Here, we present a study of the spectral age of two powerful, cluster-center radio galaxies, and compare with an analytic model to robustly determine their jet powers. We also present some recent LOFAR observations of the different phases of RLAGN activity, namely the remnant and subsequent restarting phases, which are key to understanding the dynamics of RLAGN over their total lifetime.

The stellar disc of the Milky Way exhibits clear departures from planarity, the most conspicuous manifestation being the Galactic Warp but also includes an apparent corrugation pattern in number counts around 15kpc from the Galactic centre, a wave like pattern in the vertical velocities of stars as a function of guiding radius, asymmetries about the midplane in both number counts and bulk motions, and phase spirals in the z–vz projection of the local stellar distribution function. We discuss the physics of these phenomena and, in particular, suggest a possible avenue for inferring the vertical force in the Solar Neighbourhood from phase spirals. We apply Dynamic Mode Decomposition, a technique widely used in the realm of fluid mechanics, to simulations of disc galaxy simulations. This method appears to be particularly well-suited to the study of nonlinear processes such as the coupling of warps and spirals, first discussed by Masset and Tagger.

We built the most extended stellar density and/or surface brightness radial profiles for 13 old Large Magellanic Cloud (LMC) globular clusters (GCs). The studied GCs located farther than ~ 5 kpc from the LMC center would not seem to present any hint of extended stellar structures, while those closer than ~ 5 kpc do show extended structures. Such an excess of stars tightly depends on the position of the GCs, so that the closer the GC to the LMC center, the larger the excess of stars. Furthermore, the GC radii also show a remarkable trend with the position of the GC in the LMC disc. These outcomes can be fully interpreted in the light of the known GC radial velocity disc-like kinematics, from which GCs have been somehow mostly experiencing the influence of the LMC gravitational field at their respective mean distances from the LMC center.

We show that the structure of magnetized accretion gas flows between the components of the Beta Lyrae system can cause a scattering gas shell that masks completely these components in soft X-ray region. Also we have calculated the inner structure of the donor that is filling a Roche lobe and is preceding a forming of the degenerate dwarf. We show that mass of the degenerate core of the donor is in region 0.3−0.5M⊙.

The Milky Way’s stellar halo preserves a fossil record of smaller dwarf galaxies that merged with the Milky Way throughout its formation history. Currently, though, we lack reliable ways to identify which halo stars originated in which dwarf galaxies or even which stars were definitively accreted. Selecting stars with specific chemical signatures may provide a way forward. We investigate this theoretically and observationally for stars with r-process nucleosynthesis signatures. Theoretically, we combine high-resolution cosmological simulations with an empirically-motivated treatment of r-process enhancement. We find that around half of highly r-process-enhanced metal-poor halo stars may have originated in early ultra-faint dwarf galaxies that merged into the Milky Way during its formation. Observationally, we use Gaia DR2 to compare the kinematics of highly r-process-enhanced halo stars with those of normal halo stars. R-process-enhanced stars have higher galactocentric velocities than normal halo stars, suggesting an accretion origin. If r-process-enhanced stars largely originated in accreted ultra-faint dwarf galaxies, halo stars we observe today could play a key role in understanding the smallest building blocks of the Milky Way via this novel approach of chemical tagging

Understanding how, when and where complex organic and potentially prebiotic molecules are formed is a fundamental goal of astrochemistry. Since its beginning the Atacama Large Millimeter/submillimeter Array (ALMA) has demonstrated its capabilities for studies of the chemistry of solar-type stars. Its high sensitivity and fine spectral and angular resolution makes it possible to study the chemistry of young stars on Solar System scales. We here present an unbiased spectral survey, Protostellar Interferometric Line Survey (PILS), of the astrochemical template source and Class 0 protostellar binary IRAS 16293-2422 using ALMA. The high quality ALMA data have allowed us to detect a wealth of species previously undetected toward solar-type protostars as well as the interstellar medium in general. Also, the data show the presence of numerous rare isotopologues of complex organic molecules and other species: the exact measurements of the abundances of the complex organic molecules and their isotopologues shed new light onto the formation of these species and provide a chemical link between the embedded protostellar stages and the early Solar System.

Evolved low- and intermediate-mass stars that have reached the Asymptotic Giant Branch (AGB) phase tend to show pronounced long-period variability due to large-amplitude pulsations. Those pulsations are considered to play a key role in triggering mass loss through massive dusty winds. The winds enrich the surrounding interstellar medium with newly-produced chemical elements and dust grains, providing building blocks for new generations of stars and planets. Considerable efforts are being made to understand the physics of AGB stars, and to develop quantitative models. This talk gave a brief summary of recent developments, with references to the literature.

Some ultra-compact dwarf galaxies have large dynamical mass to light (M / L) ratios and also appear to contain an overabundance of LMXB sources, and some Milky Way globular clusters have a low concentration and appear to have a deficit of low-mass stars. These observations can be explained if the stellar IMF becomes increasingly top-heavy with decreasing metallicity and increasing gas density of the forming object. The thus constrained stellar IMF then accounts for the observed trend of metallicity and M / L ratio found amongst M31 globular star clusters. It also accounts for the overall shift of the observationally deduced galaxy-wide IMF from top-light to top-heavy with increasing star formation rate amongst galaxies. If the IMF varies similarly to deduced here, then extremely young very massive star-burst clusters observed at a high redshift would appear quasar-like (Jerabkova et al. 2017).

We derive azimuthally-averaged surface-brightness profiles of 16 AGB stars in the far-IR and sub-mm with the aim of studying the resolved historic mass loss in the extended circumstellar envelope. The PSF-subtracted extended component fluxes were found to be ∼40% of the total source flux. By fitting SEDs at each radial point we derive the dust temperature, column density and spectral index of emissivity via Bayesian inference. The measured dust-to-gas ratios were somewhat consistent with canonical values however with a large scatter.

The Perseus cluster is the X-ray brightest cluster in the sky and with deep Chandra observations we are able to map its central structure on very short spatial scales. In addition, the high quality of X-ray data allows detailed spatially-resolved spectroscopy. In this paper I review what these deep observations have told us about AGN feedback in clusters, sloshing and instabilities, and the metallicity distribution.

Global history of star or cluster formation in the Large Magellanic Cloud (LMC) has been the center of interest in several studies as it is thought to be influenced by tidal interaction with the Small Magellanic Cloud and even the Milky Way. This study focus on the formation history of the LMC in relation with the context of binary star clusters population, the apparent binary fraction (e.g., percentage of cluster pairs) in different epoch were calculated and analyzed. From the established distributions, it can be deduced that the binary clusters tend to be young (∽ 100 Myr) while their locations coincide with the locations of star forming complexes. There is an indication that the binary fraction increases as the rise of star formation rate in the last millions years. In the LMC, the increase of binary fraction at age ∽ 100 Myr can be associated to the last episode of close encounter with the Small Magellanic Cloud at ∽ 150 Myr ago. This observational evidence supports the theory of binary cluster formation through the fission of molecular cloud where the encounter between galaxies enhanced the clouds velocity dispersion which in turn increased the probability of cloud-cloud collisions that produce binary clusters.

This talk discussed the basics of gravito-inertial asteroseismology as recently developed for stars born with a convective core. Photometric space missions originally built for exoplanet hunting, notably Kepler, have opened up the low-frequency regime of stellar oscillations and revealed a larger diversity in variability than anticipated prior to the era of high-precision space photometry. The talk explained the basics of forward seismic modelling based on gravito-inertial modes, which probe the deep stellar interior. It described how a hierarchical fitting approach allows us to derive the near-core rotation period, the amount and shape of convective core overshooting, and the level of chemical mixing in the radiative envelope for stars born with a convective core and burning hydrogen in their core. A summary of the current status, covering the mass range 1.4 ≲ M ≲ 5 M⊙, is provided here through references to numerous recent papers.

The mass loss process along the AGB phase is crucial for the formation of circumstellar envelopes (CSEs), which in the post-AGB phase will evolve into planetary nebulae (PNe). There are still important issues that need to be further explored in this field; in particular, the formation of axially symmetric PNe from spherical CSEs. To address the problem, we have conducted high S/N IRAM 30 m observations of 12COJ = 1−0 and J = 2−1, and 13COJ = 1−0 in a volume-limited unbiased sample of semi-regular variables (SRs). We also conducted Yebes 40 m SiO J = 1−0 observations in 1/2 of the sample in order to complement our 12CO observations. We report a moderate correlation between mass loss rate and the 12CO(1−0)−to−12CO(2−1) line intensity ratio, introducing a possible new method for determining mass loss rates of SRs with short analysis time. We also find that for several stars the SiO profiles are very similar to the 12CO profiles, a totally unexpected result unless these are non-standard envelopes.

We analyse archival XMM-Newton observations of the massive galaxy group NGC 4839 falling into the Coma cluster core, which reveal a complex morphology for the merger. By comparing high quality X-ray maps of the merging subcluster with SPH simulations, we propose an infall scenario which qualitatively reproduces the observed structure of the NGC 4839 tail.

The photometric properties that we could observe for Extra-Galactic Globular Clusters (EGGCs) are the integrated light of the system and for nearby EGGCs it also is possible to measure both half-light radii and the color spatial distribution, e.g. for areas smaller and larger than the half-light radius. No information about the internal dynamical state of the system could be directly obtained from observations. On the other hand, simulations of Globular Clusters (GCs) can provide detailed information about the dynamical evolution of the system.

We present a preliminary study of EGGCs’ photometric properties for different dynamical evolutionary stages. We apply this study to 12Gyr old GCs simulated as part of the MOCCA Survey Database. We determine the magnitudes in different bands from their projected snapshots using the Flexible Stellar Population Synthesis (FSPS) code and we measure the half-light radii from the surface brightness.