We observed the 2 July 2019 total solar eclipse with a variety of imaging and spectroscopic instruments recording from three sites in mainland Chile: on the centerline at La Higuera, from the Cerro Tololo Inter-American Observatory, and from La Serena, as well as from a chartered flight at peak totality in mid-Pacific. Our spectroscopy monitored Fe X, Fe XIV, and Ar X lines, and we imaged Ar X with a Lyot filter adjusted from its original H-alpha bandpass. Our composite imaging has been compared with predictions based on modeling using magnetic-field measurements from the pre-eclipse month. Our time-differenced sites will be used to measure motions in coronal streamers.

New observations are probing the structures and kinematics of massive galaxies at a much greater level of detail than previously possible, especially during the first half of cosmic history. ALMA data now resolve the distribution of dust and molecular gas in massive galaxies to z ˜ 5. The stellar kinematics of several massive galaxies at z ˜ 2 – 3 have been spatially resolved using gravitational lensing, providing new information on the connection between quenching and morphological transformation. Star formation histories have been reconstructed for growing samples at z ˜ 0.8–2, revealing a wide range of timescales that correlate with galaxies’ sizes and environments, providing evidence for multiple paths to quiescence. I review these and other developments and summarize the insights they have provided into massive galaxies’ evolution.

In the past decade hundreds of galaxies have been identified in the Epoch of Reionisation, selected from their rest-frame UV light. Only a handful of these sources, however, have spectroscopic redshift determinations and we have limited understanding of their physical properties. ALMA is currently transforming this field by providing the first view of the dust obscured star-formation, the kinematics of these sources, the cool gas traced by [CII] and highly ionised gas traced by [OIII]. In this talk I will discuss new and recent results on the UV-bright galaxy population during the first billion years of cosmic time and what they imply for their observational and physical properties.

This paper presents a short review on the current state of SN Ia progenitor origin. Type Ia supernova explosions (meaning thermonuclear disruption of a white dwarf) are observed to be widely diverse in peak luminosity, lightcurve width and shape, spectral features, and host stellar population environment. In the last decade alone, theoretical simulations and observational data have come together to seriously challenge the long-standing paradigm that all SNe Ia arise from explosions of Chandrasekhar mass white dwarfs. In this review I highlight some of the major developments (and changing views) of our understanding of the nature of SN Ia progenitor systems. I give a brief overview of binary star configurations and their plausible explosion mechanisms, and infer links between some of the various (observationally-categorized) SN Ia sub-classes and their progenitor origins from a theoretical standpoint.

In this paper we summarise the research that is currently going on in Ethiopia and East-Africa in extragalactic astronomy and physics of active galaxies and active galactic nuclei (AGN). The study is focused on some of the still open questions such as: what are the stellar ages and populations of ultra hard X-ray detected AGN and connection between AGN and their host galaxies?, what are the properties of AGN in galaxy clusters and the role that environment has in triggering nuclear activity?, what are the morphological properties of AGN and how precisely we can deal with morphological classification of active galaxies?, what are the properties of galaxies in the green valley and the role of AGN in galaxy evolution?, and what are the properties of radio-loud and radio-quiet quasars (QSO) and dichotomy between the two?. Each of these questions has been developed under one specific project that will be briefly introduced. These projects involve 6 PhD and 3 MSc students and collaborations between Ethiopia, Rwanda, South Africa, Uganda, Tanzania, Spain, Italy, and Chile. With all projects we aim: first, to contribute to our general knowledge about AGN, and second, to contribute to the development in astronomy and science in Ethiopia and East-Africa.

This paper provides a brief overview of the many facets of astronomy education and heritage, and how the IAU stimulates them. Activities range from training in astronomy through scientific meetings and schools for young astronomers, to using astronomy as a tool for development and for stimulating science education at school level. Communicating astronomy with the public and engaging in outreach activities with children to inspire curiosity is yet another way of how astronomy can help build a literate society and install a sense of global citizenship. The involvement of many people at all levels is key to success.

We have shown that in the inner belt the loss of asteroids from the ν6 secular resonance and the 3:1 Jovian mean motion resonance accounts for the observation that the mean size of the asteroids increases with increasing orbital inclination. We have used that observation to constrain the Yarkovsky loss timescale and to show that the family asteroids are embedded in a background population of old ghost families. We argue that all the asteroids in the inner belt originated from a small number of asteroids and that the initial mass of the belt was similar to that of the present belt. We also show that the observed size frequency distribution of the Vesta asteroid family was determined by the action of Yarkovsky forces, and that the age of this family is comparable to the age of the solar system.

Astronomy has changed from data-starving science to data-flooding science about 20 years ago due to advances of observational technology in all the wavelength regimes of electromagnetic waves. This paper gives a historical overview of galaxy surveys. We start from the impact of the technology development. Then, old imaging surveys and redshift surveys based on photography, especially using Schmidt telescopes, in the era of data-starving science are described in some detail. Several features of modern surveys are given and two highlights obtained from the exploitation of modern galaxy surveys are introduced.

This brief overview stresses the importance of laboratory data and theory in analyzing astronomical observations and understanding the physical and chemical processes that drive the astrophysical phenomena in our Universe. This includes basic atomic and molecular data such as spectroscopy and collisional rate coefficients, but also an improved understanding of nuclear, plasma and particle physics, as well as reactions and photoprocesses in the gaseous and solid state that lead to chemical complexity and building blocks for life. Systematic laboratory collision experiments have provided detailed insight into the steps that produce pebbles, bricks and ultimately planetesimals starting from sub-μ-sized grains. Sample return missions and meteoritic studies benefit from increasingly sophisticated laboratory machines to analyze materials and provide compositional images on nanometer scales. Prioritization of future data requirements will be needed to cope with the increasing data streams from a diverse range of future astronomical facilities within a constrained laboratory astrophysics budget.

The surfaces of interstellar and circumstellar dust grains are the sites of molecule formation, most of which, except H2, stick and form ice mantles. The study of ice evolution thus seems directly relevant for understanding our own origins, although the relation between interstellar and solar system ices remains a key question. The comparison of interstellar and solar system ices relies evidently on an accurate understanding of the composition and processes in both environments. With the accurate in situ measurements available for the comet 67P/Churyumov-Gerasimenko with the Rosetta mission, improving our understanding of interstellar ices is the more important. Here, I will address three specific questions. First, while laboratory experiments have made much progress in understanding complex organic molecule (COM) formation in the ices, the question remains, how does COM formation depend on environment and time? Second, what is the carrier of sulfur in the ices? And third, can ice absorption bands trace the processing history of the ices? Laboratory experiments, ranging from infrared spectroscopy to identify interstellar ice species, to surface experiments to determine reaction parameters in ice formation scenarios, to heating and irradiation experiments to simulate space environments, are essential to address these questions and analyze the flood of new observational data that will become available with new facilities in the next 2-10 years.

Models for massive black holes are a key ingredient for modern cosmological simulations of galaxy formation. The necessity of efficient AGN feedback in these simulations makes it essential to model the formation, growth and evolution of massive black holes, and parameterize these complex processes in a simplified fashion. While the exact formation mechanism is secondary for most galaxy formation purposes, accretion modeling turns out to be crucial. It can be informed by the properties of the high redshift quasars, accreting close to their Eddington limit, by the quasar luminosity function at peak activity and by low-redshift scaling relations. The need for halo-wide feedback implies a feedback-induced reduction of the accretion rate towards low redshift, amplifying the cosmological trend towards lower accretion rates at low redshift.

Thanks to deep optical to near-IR imaging and spectroscopy, significant progress is made in characterizing the rest-frame UV to optical properties of galaxies in the early universe (z > 4. Surveys with Hubble, Spitzer, and ground-based facilities (Keck, Subaru, and VLT) provide spectroscopic and photometric redshifts, measurements of the spatial structure, stellar masses, and optical emission lines for large samples of galaxies. Recently, the Atacama Large (Sub) Millimeter Array (ALMA) has become a major player in pushing studies of high redshift galaxies to far-infrared wavelengths, hence making panchromatic surveys over many orders of frequencies possible. While past studies focused mostly on bright sub-millimeter galaxies, the sensitivity of ALMA now enables surveys like ALPINE, which focuses on measuring the gas and dust properties of a large sample of normal main-sequence galaxies at z > 4. Combining observations across different wavelengths into a single, panchromatic picture of galaxy formation and evolution is currently and in the future an important focus of the astronomical community.

Mingantu Spectral Radioheliograph (MUSER) is an aperture-synthesis imaging telescope, dedicated to observe the Sun, operating on multiple frequencies in dm to cm range. The ability of MUSER to get images and measure Stokes I and V parameters simultaneously at many frequencies in a wide band is of fundamental importance. It allows one to approach/solve such important problems as measuring the strength, geometry and dynamics of magnetic field at coronal heights. Here we consider some of the recently developed radio physics methods to be used for solving the problems. These methods allow us to obtain information that is unattainable in other areas of the electromagnetic spectrum.

I discuss the second IAU Strategic Plan for the decade 2020–30 in the context of the overall evolution of the IAU in recent past decades. This article shows how the IAU has evolved dramatically since WW2. It is hardly recognizable in terms of its original organization and goals of a century ago. What was once an inward-looking body engaged purely with the procedures of astronomical research is now a dynamic and outward-looking organization, interacting with people, especially students and the public.

A large part of this success must be attributed to the IAU’s unique body of individual members, whose number has grown strongly in recent decades. It is the individual members, especially through the Commissions and Working Groups, who have promoted these enormous changes in the outlook of the Union. This is a model for other scientific unions to follow, and especially for the work to promote the careers of women in science, for promoting the careers of young astronomers, for bringing students into astronomy or into science in general, for helping people with disabilities to have careers in astronomy, for engaging with the public, and for helping to develop astronomy and science in developing countries.

Looking to the future, the IAU’s new Strategic Plan for the years 2020 to 2030 has five major goals for the coming decade: 1. The IAU leads the worldwide coordination of astronomy and the fostering of communication and dissemination of astronomical knowledge among professional astronomers. 2. The IAU promotes the inclusive advancement of the field of astronomy in every country. 3. The IAU promotes the use of astronomy as a tool for development in every country. 4. The IAU engages the public in astronomy through access to astronomical information and communication of the science of astronomy. 5. The IAU stimulates the use of astronomy for teaching and education at school level.

Future developments will also be engaging with the large number of amateur astronomers and helping to promote astro-tourism, which is perhaps the new frontier now growing rapidly around the world. The Strategic Plan is a blueprint for forging a social revolution in astronomy and for using astronomy as a tool for building a progressive society.

Formation of close double white dwarfs likely requires the initial binary system to evolve through two successive common envelope (CE) phases. A prominent method for describing CE outcomes involves defining an ejection efficiency, αeff, which quantifies the fraction of orbital energy available to unbind the envelope. Reproducing observed post-CE orbital parameters has proven difficult for numerical simulations, as the companion’s decaying orbit fails to eject the envelope. The ejection failure seen in numerical simulations may be resolved with a proper treatment of convection, whereby the binary orbit shrinks before energy can drive ejection. Where the orbital decay timescale exceeds the convective transport timescale, the energy released during inspiral is carried to the stellar surface and radiated away. By including convection, we produce sub-day post-CE orbital periods, a result consistent with observations. We comment on the effects of convection for the population of double white dwarfs that evolve through two CEs.

Most of what we know about active galactic nuclei (AGNs) has been driven, or at least strongly shaped, by our methods for finding them, and multiwavelength AGN surveys have achieved remarkable successes in recent decades. I will present a broad, and thus necessarily shallow, review of such multiwavelength AGN surveys. I will first present some brief introductory points on, e.g., general survey approaches, AGN luminosities, host galaxies, and anisotropic emission/obscuration. I will then review many of the key current surveys and their results, separating these into ground-based and space-based surveys. Finally, I will discuss some future prospects including essential remaining questions and “discovery space” considerations.

This paper reviews the basic equations used in the study of the tidal variations of the rotational and orbital elements of a system formed by one star and one close-in planet as given by the creep tide theory and Darwin’s constant time lag (CTL) theory. At the end, it reviews and discusses the determinations of the relaxation factors (and time lags) in the case of host stars and hot Jupiters based on actual observations of orbital decay, stellar rotation and age, etc. It also includes a recollection of the basic facts concerning the variations of the rotation of host stars due to the leakage of angular momentum associated with stellar winds.

While the high-redshift component of the CANDELS survey was designed with the z ∼ 6–8 era in mind, these data do probe the far-UV of galaxies at even higher redshift. A few studies have ventured this far out, and have published conflicting results - some continue to find significant star-formation, while others conclude there is a steep decline in this quantity. Here I report on a new search for z = 9–10 galaxies, making significant use of the Spitzer/IRAC data in the CANDELS fields. We have discovered a larger number of galaxies in this epoch than previous works, implying the UV luminosity function, and thus the SFR density, may not evolve as steeply as previously thought. This implies that star-formation begins early in the universe. I will also report on a new study searching for the earliest quenched galaxies at 3 < z < 5, which are not predicted by models, yet may exist if galaxies form very early, and thus can approach their quenching phase quicker.

Over the last few years, great progress has been made in understanding the build-up of the first generations of galaxies based on deep optical and near-infrared imaging from the Hubble Space Telescope. However, HST only samples the rest-frame UV light of galaxies at z …4, providing only limited information on the dust obscuration and on stellar masses of these sources. Fortunately, several Spitzer/IRAC programs have complemented the extragalactic HST fields with ultra-deep imaging data, allowing for a rest-frame optical view on early galaxies. Together with first ALMA/ NOEMA (sub)mm observations on distant galaxies, we are starting to gain a more and more complete picture of galaxy star-formation and mass build-up in the early universe. In this talk, I will present an overview of our current understanding of normal star-forming galaxies at z > 3 based the combination of HST+Spitzer+ALMA/NOEMA data. In particular, I will show how HST as already pushed into JWST territory with the discovery and spectroscopic confirmation of a galaxy at z = 11.1 ± 0.1, only : 400 Myr after the Big Bang. I will also highlight some of the exciting possibilities that lie ahead with JWST to push the spectroscopic frontier to the cosmic dawn and to finally probe the physics of early galaxies.

The coexistence of star formation and AGN activity has geared much attention to dusty galaxies at high redshifts, in the interest of understanding the origin of the Magorrian relation observed locally, where the mass of the stellar bulk in a galaxy appears to be tied to the mass of the underlying supermassive black hole. We exploit the combined use of far-infrared (IR) Herschel data and deep Chandra ˜160 ksec depth X-ray imaging of the COSMOS field to probe for AGN signatures in a large sample of >100 Dust-Obscured Galaxies (DOGs). Only a handful (˜20%) present individual X-ray detections pointing to the presence of significant AGN activity, while X-ray stacking analysis on the X-ray undetected DOGs points to a mix between AGN activity and star formation. Together, they are typically found on the main sequence of star-forming galaxies or below it, suggesting that they are either still undergoing significant build up of the stellar bulk or have started quenching. We find only ˜30% (6) Compton-thick AGN candidates (NH > 1024 cm–2), which is the same frequency found within other soft- and hard-X-ray selected AGN populations. This suggests that the large column densities responsible for the obscuration in Compton-thick AGNs must be nuclear and have little to do with the dust obscuration of the host galaxy. We find that DOGs identified to have an AGN share similar near-IR and mid-to-far-IR colors, independently of whether they are individually detected or not in the X-ray. The main difference between the X-ray detected and the X-ray undetected populations appears to be in their redshift distributions, with the X-ray undetected ones being typically found at larger distances. This strongly underlines the critical need for multiwavelength studies in order to obtain a more complete census of the obscured AGN population out to higher redshifts. For more details, we refer the reader to Riguccini et al. (2019).