We present photo-ionization and morpho-kinematic analyses of the ejecta of novae. The sample consists of ten novae belonging to the Fe II, He/N and hybrid classes. The Fe II class of novae in the sample have bipolar cone-like structures, with or without equatorial rings with inclination angle in the range of 40°–60°. The He/N novae have bullet-nose curve along with bipolar cone-like structures and equatorial rings with an inclination angle of ~80°. The hybrid nova in the sample is a bipolar frustum of prolate spheroid along with bipolar cone-like structures and equatorial rings with an inclination angle of 63°.

Galaxy groups offer an important perspective on how the large-scale structure of the Universe has formed and evolved, being great laboratories to study the impact of the environment on the evolution of galaxies. We aim to investigate the properties of a galaxy group that is gravitationally lensing HELMS18, a submillimeter galaxy at z = 2.39. We obtained multi-object spectroscopy data using Gemini-GMOS to investigate the stellar kinematics of the central galaxies, determine its members and obtain the mass, radius and the numerical density profile of this group. Our final goal is to build a complete description of this galaxy group. In this work we present an analysis of its two central galaxies: one is an active galaxy with z = 0.59852 ± 0.00007, while the other is a passive galaxy with z = 0.6027 ± 0.0002. Furthermore, the difference between the redshifts obtained using emission and absorption lines indicates an outflow of gas with velocity v = 278.0 ± 34.3 km/s relative to the galaxy.

The mid-IR spectrum of the interstellar medium contains both aromatic and aliphatic hydrocarbon features. These are generally attributed to carbonaceous dust. The aliphatic component is of particular interest because it produces a significant 3.4 μm absorption feature. The optical depth of this feature is related to the number and type of aliphatic carbon C–H bonds in the line of sight. It is possible to estimate the column density of aliphatic carbon from quantitative analysis of the 3.4 μm interstellar feature, providing that the absorption coefficient of interstellar aliphatic hydrocarbon is known. We produced interstellar dust analogues with spectra closely matching astronomical observations. Using a combination of FTIR and 13C NMR spectroscopy, we determined an integrated absorption coefficient of the aliphatic component. The results thus obtained permit direct calibration of astronomical observations, providing rigorous estimates of the amount of aliphatic carbon in the ISM.

The hot Jupiter HD189733b is expected to be a source of strong radio emission, due to its close proximity to its magnetically active host star. Here, we model the stellar wind of its host star, based on reconstructed surface stellar magnetic field maps. We use the local stellar wind properties at the planetary orbit obtained from our models to compute the expected radio emission from the planet. Our findings show that the planet emits with a peak flux density within the detection capabilities of LOFAR. However, due to absorption by the stellar wind itself, this emission may be attenuated significantly. We show that the best time to observe the system is when the planet is near primary transit of the host star, as the attenuation from the stellar wind is lowest in this region.

The programme of this IAU Symposium, number 357, consisted of sessions organized around a number of key themes, as detailed in the preceding text. Each session included one or two invited keynote talks plus a number of contributed papers. Time was set aside for extensive discussion following the sessions associated with each of them. These were moderated by members of the Science Organising Committee, posing a number of questions to the audience to stimulate the discussion. The nature of such discussions makes them hard to record in detail, but a number of key points have been extracted and incorporated into this short concluding paper.

Recently, spectroscopic detections of O[III] 88 μm and Ly-α emission lines from the z ≍ 9.1 galaxy MACS1149-JD1 have been presented, and with these, some interesting properties of this galaxy were uncovered. One such property is that MACS1149-JD1 exhibits a significant Balmer break at around rest-frame 4000 Å, which may indicate that the galaxy has experienced large variations in star formation rate prior to z ∼ 9, with a rather long period of low star formation activity. While some simulations predict large variations in star formation activity in high-redshift galaxies, it is unclear whether the simulations can reproduce the kind of variations seen in MACS1149-JD1. Here, we utilize synthetic spectra of simulated galaxies from two simulation suites in order to study to what extent these can accurately reproduce the spectral features (specifically the Balmer break) observed in MACS1149-JD1. We show that while the simulations used in this study produce galaxies with varying star formation histories, galaxies such as MACS1149-JD1 would be very rare in the simulations. In principle, future observations with the James Webb Space Telescope may tell us if MACS1149-JD1 represents something rare, or if such galaxies are more common than predicted by current simulations.

Accretion of matter onto central Black Holes (BHs) in galaxies liberates enormous amounts of feedback energy, which affects the environment from pc to Mpc scales. These BHs are usually Supermassive BHs (SMBHs: mass ⩾106M⊙) existing at the centers of active galactic nuclei (AGN), which are widely observed through their multi-wavelength emission at all cosmic epochs. Relatively recently, Intermediate-Mass BHs (IMBHs: mass = 100−106M⊙) have started to be observed hosted in Dwarf Galaxy (DG) centers. Some of the central IMBHs in DGs show signatures of activity in the form of low-luminosity AGN. We have performed Cosmological Hydrodynamical Simulations to probe SMBHs in high-z quasars (Barai et al. 2018), and IMBHs in DGs (Barai & de Gouveia Dal Pino 2019). Our simulations employ the 3D TreePM SPH code GADGET-3, and include metal cooling, star formation, chemical enrichment, stellar evolution, supernova feedback, AGN accretion and feedback. Analyzing the simulation output in post-processing, we investigate the growth of the first IMBHs and the first SMBHs, as well as their impact on star-formation.

Asymptotic Giant Branch (AGB) stars contribute a major part to the global dust budget in galaxies. Owing to their refractory nature alumina (stoichiometric formula AlO) is a promising candidate to be the first condensate emerging in the atmospheres of oxygen-rich AGB stars. Strong evidence for that is supplied by the presence of alumina in pristine meteorites and a broad spectral feature observed around ∼ 13 μm. The emergence of a specific condensate depends on the thermal stability of the solid, the gas density and its composition. The evaluation of the condensates is based on macroscopic bulk properties. The growth and size distribution of dust grains is commonly described by Classical Nucleation Theory (CNT). We question the applicability of CNT in an expanding circumstellar envelope as CNT presumes thermodynamic equilibrium and requires, in practise, seed nuclei on which material can condense. However, nano-sized molecular clusters differ significantly from bulk analogues. Quantum effects of the clusters lead to non-crystalline structures, whose characteristics (energy, geometry) differ substantially, compared to the bulk material. Hence, a kinetic quantum-chemical treatment involving various transition states describes dust nucleation most accurately. However, such a treatment is prohibitive for systems with more than 10 atoms. We discuss the viability of chemical-kinetic routes towards the formation of the monomer (Al2O3) and the dimer (Al4O6) of alumina.

A large-scale structure has been recently discovered at z = 1.7, around a powerful FRII radio galaxy. Eight Star Forming Galaxies (SFGs) have been discovered within Δ z ≍ 0.0095 and at < 1 Mpc from the FRII, indicating that this is a signpost of a protocluster. Furthermore, a significant X-ray diffuse emission overlapping the Eastern lobe of the FRII has been detected. Protoclusters are the ideal targets to investigate the complex assembly processes leading to the formation of local galaxy clusters. We will exploit new ALMA CO(2-1) observations (PI: R. Gilli) of the entire region around the FRII galaxy to trace the molecular gas content, in order to discover new protocluster members. Coupling these measurements with the multi-wavelength data coverage available for this field, we aim at placing constrains on the physical conditions in which star formation occurs, and ultimately infer the role of the radio jets in triggering it.

Post-starburst galaxies (PSBGs) are systems that experienced a burst followed by a rapid quenching of star formation. However, it is still unclear what causes these events and what is the environmental role in the origin of PSBGs. To address this, we analysed sizes, morphologies, ages, and metallicities of PSBGs at 0.05 ≤ z ≤ 0.1 in groups and clusters of galaxies. We find a statistically significant excess of compact PSBGs in groups compared to a control sample of passive galaxies. Satellite PSBGs in groups tend to be more compact compared to their counterparts in clusters. Additionally, the PSBGs in groups have smaller T-type values and are likely to be found in inner group regions compared to PSBGs in clusters. Our results are compatible with dissipative wet merger events being an important mechanism responsible for the origin of PSBGs in groups, but other – less dissipative – processes may be producing PSBGs in cluster environments.

Ionized winds from late-type main-sequence stars are important for stellar spin-down and therefore the evolution of stellar activity; winds blow an “astrosphere” into the interstellar medium that absorbs a large part of galactic cosmic rays; and the winds play a key role in shaping planetary environments, in particular their upper atmospheres. These issues have been well studied for the solar wind but little is known about winds escaping from other solar-type stars. Several methods have been devised to either detect winds directly or to infer the presence of such winds from features that are shaped by the winds. This paper summarizes these methods and discusses exemplary findings. There is need for more studies using multiple methods for the same stars.

Cultural astronomy is the study of the astronomy of ancient cultures and is sometimes called the anthropology of astronomy. The many ways that astronomy was used by ancient cultures are fascinating and this can be used to inspire interest in all astronomy, as well as astronomy in culture. Archaeoastronomy is interdisciplinary and among its practitioners are not only astronomers and astrophysicists, but also anthropologists, archaeologists, and Indigenous scholars. Much can be learned about ancient cultures though examination of how and why they used astronomy. This paper will highlight several examples that can capture public attention.

We conduct a survey for Lyman break galaxies (LBGs) and Lyman alpha emitters (LAEs) in the environs of six and 17 z ∼ 4 quasars respectively, probing scales of R≲9h−1Mpc. We detect an enhancement of galaxies (both LBGs and LAEs) in quasar fields, a positive and strong quasar-galaxy cross-correlation function, consistent with a power-law shape, and a strong galaxy auto-correlation function in quasar fields. The three mentioned results are all indicators that quasars trace massive dark matter halos in the early universe.

We present white light images of the Sun's corona acquired during the total Solar Eclipses on August 21, 2017 in mountains north of Boise Idaho USA and on July 2, 2019 south of Copiapo Chile. In both cases the viewing was excellent, altitudes ∼ 1200 m and relative humidity ∼ 10. We used an Orion equatorial reflecting telescope with 203 mm diameter aperture and 1000 mm focal length for f4.9 optics. A computer-controlled Canon EOS Rebel T3i digital camera was used. We plan to use our 2019 eclipse images for analysis since the Sun is near solar minimum so 2D steady state MHD equations can be used. We present a plan to process the images and convert them into a 2D empirical model of electron density and magnetic field in radial distance and co-latitude, from which 2D maps of flow velocity, effective temperature and effective heat flux can be computed.

Astronomy in Armenia was popular since ancient times and Armenia is rich in its astronomical heritage, such as ancient and medieval Armenian calendars, records of astronomical events by ancient Armenians, the astronomical heritage of the Armenian medieval great thinker Anania Shirakatsi, etc. Armenian astronomical archives have accumulated vast number of photographic plates, films and other careers of observational data. The Digitized Markarian Survey or the First Byurakan Survey, is the most important low-dispersion spectroscopic database. It is one of the rare science items included in UNESCO “Memory of the World” Documentary Heritage list. The Byurakan Astrophysical Observatory (BAO) Plate Archive Project (2015–2021) will result in digitization and storage of some 37,000 astronomical plates and films and in creation of an Electronic Database for further research projects. Based on these data and archives and development of their interoperability, the Armenian Virtual Observatory was created and joined the International Virtual Observatory Alliance.

We estimate the wind speeds with a Bayesian inference and a Markov Chain Monte Carlo (MCMC) tool for the high resolution X-ray spectra of Vela X-1, to understand the effect of satellite lines on spectral analysis. After modelling continua and He-like triplets of the spectra with a parameterized two-component power-law model and a mullti-Gaussian model, respectively, we estimate the contamination from satellite lines, and improve the self-consistency of wind speeds derived from the He-like triplet lines of different elements. Moreover, our fitting shows that the column density of scatter component varies from phase to phase.

AGN feedback, through either radiation or kinematics by expelled medium, plays a crucial role in the coevolution of supermassive black hole (SMBH) and its host galaxy. The nuclei spend most of their time as low-luminosity AGNs (LLAGNs), whose spectra are distinctive to bright AGNs, and the feedback is the hot mode (also named kinetic mode). We thus investigate the radiative heating in the hot mode. We calculate the value of “Compton temperature” Tc, which defines the heating capability of the radiation at given flux, and find that Tc∼(5−15)×107 K, depending on the spectrum of individual LLAGNs. This work provides a cheap way to include the radiative heating of LLAGNs in the study of AGN feedback.

Galaxy mergers are known to drive an inflow of gas towards galactic centers, potentia- lly leading to both star formation and nuclear activity. In this work we aim to study how a major merger event in the ARP 245 system is linked with the triggering of an active galactic nucleus (AGN) in the NGC galaxy 2992. We employed three galaxy collision numerical simulations and calculated the inflow of gas through four different concentric spherical surfaces around the galactic centers, estimating an upper limit for the luminosity of an AGN being fed the amount of gas crossing the innermost spherical surface. We found that these simulations predict reasonable gas inflow rates when compared with the observed AGN luminosity in NGC 2992.

We report fourteen and twenty-eight protocluster candidates at z = 5.7 and 6.6 over 14 and 19 deg2 areas, respectively, selected from 2,230 Lyα emitters (LAEs) photometrically identified with Subaru/Hyper Suprime-Cam (HSC) deep images. Six out of the 42 protocluster candidates include at least 1 spectroscopically confirmed LAEs at redshifts up to z = 6.574. By the comparisons with the cosmological Lyα radiative transfer (RT) model reproducing LAEs with the reionization effects, we find that more than a half of these protocluster candidates might be progenitors of the present-day clusters with a mass of ≳ 1014M⊙. We also investigate the correlation between LAE overdensity and Lya rest-frame equivalent width (EW), because the cosmological Lyα RT model suggests that a slope of EW-overdensity relation is steepened towards the epoch of cosmic reionization (EoR), due to the existence of the ionized bubbles around galaxy overdensities easing the escape of Lyα emission from the partly neutral intergalactic medium. The available HSC data suggest that the slope of the EW-overdensity correlation does not evolve from the post-reionization epoch z = 5.7 to the EoR z = 6.6 beyond the moderately large statistical errors.