In this paper, we investigate the inhomogeneous spatial distribution of solar faculae. The focus is on the latitudinal and longitudinal distributions of these highly localised features covering ubiquitously the solar surface. The statistical analysis is based on white light observations of the Solar and Heliospheric Observatory (SOHO) and Solar Dynamics Observatory (SDO) between 1996 and 2014. We found that the fine structure of the latitudinal distribution of faculae displays a quasi-biennial oscillatory pattern. Furthermore, the longitudinal distribution of photospheric solar faculae does not show homogeneous behaviour either. In particular, the non-axisymmetric behaviour of these events show similar properties as that of the active longitude (AL) found in the distribution of sunspots. Our results, preliminary though, may provide a valuable observational constrain for developing the next-generation solar dynamo model.

Maser observations of both linearly and circularly polarized emission have provided unique information on the magnetic field in the densest parts of star forming regions, where non-maser magnetic field tracers are scarce. While linear polarization observations provide morphological constraints, magnetic field strengths are determined by measuring the Zeeman splitting in circularly polarized emission. Methanol is of special interest as it is one of the most abundant maser species and its different transitions probe unique areas around the protostar. However, its precise Zeeman-parameters are unknown. Experimental efforts to determine these Zeeman-parameters have failed. Here we present quantum-chemical calculations of the Zeeman-parameters of methanol, along with calculations of the hyperfine structure that are necessary to interpret the Zeeman effect in methanol. We use this model in re-analyzing methanol maser polarization observations. We discuss different mechanisms for hyperfine-state preference in the pumping of torsion-rotation transitions involved in the maser-action.

The members of the Resolutions Committee for the 2012-2015 triennium were:

• Ian Corbett (UK; Chair)

• Bruce Elmegreen (USA)

• Renée Kraan-Korteweg (South Africa)

• Yanchun Liang (China Nanjing)

• Karel van der Hucht (Netherlands)

The stellar spheroidal components of the Milky-Way contain the oldest and most metal poor of its stars. Inevitably the processes governing the early stages of Galaxy evolution are imprinted upon them. According to the currently favoured hierarchical bottom-up scenario of galaxy formation, these components, specially the Galactic halo, are the repository of most of the mass built up from accretion events in those early stages. These events are still going on today, as attested by the long stellar streams associated to the Sagittarius dwarf galaxy and several other observed tidal substructure, whose geometry, extent, and kinematics are important constraints to reconstruct the MW gravitational potential and infer its total (visible + dark) mass. In addition, the remaining system of MW satellites is expected to be a fossil record of the much larger population of Galactic building blocks that once existed and got accreted. For all these reasons, it is crucial to unravel as much of this remaining population as possible, as well as the current stellar streams that orbit within the halo. The best bet to achieve this task is to carry out wide, deep, and multi-band photometric surveys that provide homogeneous stellar samples. In this contribution, we summarize the results of several years of work towards detecting and characterizing distant MW stellar systems, star clusters and dwarf spheroidals alike, with an emphasis on the analysis of data from the Dark Energy Survey (DES). We argue that most of the volume in distance, size and luminosity space, both in the Galaxy and in the Clouds, is still unprobed. We then discuss the perspectives of exploring this outer MW volume using the current surveys, as well as other current and future surveys, such as the Large Synoptic Survey Telescope (LSST).

The first-ever revision of the sunspot number was released in 2015 by the World Data Center (WDC) SILSO. We describe the main diagnosed corrections to the sunspot and group number series, and also review newly published alternate reconstructions. We show the convergence of the determinations of the 1947 scale jump in the sunspot number around a value of 1.18 for cycle maxima. We also assess new proposed reconstructions of the group number, like the “backbone” and “active-day fraction” methods. No agreement was reached yet for this series.

We highlight the main impacts of those recent upgrades on different scientific applications. As this first revision also marks a transition towards a dynamical series open to future improvements, we finally introduce the ongoing collaborative process for preparing the next upgrade (Version 3). From now on, our scientific users must be prepared for a flexible integration of an evolving sunspot number series.

We test the hypothesis that the classical and ultra-faint dwarf spheroidal satellites of the our Galaxy have been the building blocks of the Galactic halo by comparing their [O/Fe] and [Ba/Fe] vs. [Fe/H] patterns with the ones observed in Galactic halo stars. The [O/Fe] ratio deviates substantially from the observed abundance ratios in the Galactic halo stars for [Fe/H] > -2 dex, while they overlap for lower metallicities. On the other hand, for the neutron capture elements, the discrepancy is extended at all the metallicities, suggesting that the majority of stars in the halo are likely to have been formed in situ. We present the results for a model considering the effects of an enriched gas stripped from dwarf satellites on the chemical evolution of the Galactic halo. We find that the resulting chemical abundances of the halo stars depend on the adopted infall time-scale, and the presence of a threshold in the gas for star formation.

The three years that have elapsed since the Beijing GA have been extremely rich and varied, and have seen major evolutions in the history of the IAU.

A brief history of research concerning the risk of impacts by asteroids or comets onto the Earth is presented with attention to the role played by the IAU. Special focus is placed on the events that occurred about 20 years ago, which caused the IAU to become seriously involved in dealing with the impact hazard and to take a leading role in international coordination of these activities.

Through the observations and the analysis of maser polarization it is possible to measure the magnetic field in several astrophysical environments (e.g., star-forming regions, evolved stars). In particular from the linearly and circularly polarized emissions we can determine the orientation and the strength of the magnetic field, respectively. In these proceedings the implications, on observed data, of the new estimation of the Landé g-factors for the CH3OH maser are presented. Furthermore, some example of the most recent results achieved in observing the polarized maser emission from several maser species will also be reported.

It is known that the poloidal field is at its maximum during solar minima, and that the behaviour during this time acts as a strong predictor of the strength of the following solar cycle. This relationship relies on the action of differential rotation (the Omega effect) on the poloidal field, which generates the toroidal flux observed in sunspots and active regions. We measure the helicity flux into both the northern and southern hemispheres using a model that takes account of the omega effect, which we find offers a strong quantification of the above relationship. We find that said helicity flux offers a strong prediction of solar activity up to 5 years in advance of the next solar cycle.

For fifty years astronomers have been searching for pulsar signals in observational data. Throughout this time the process of choosing detections worthy of investigation, so called ‘candidate selection’, has been effective, yielding thousands of pulsar discoveries. Yet in recent years technological advances have permitted the proliferation of pulsar-like candidates, straining our candidate selection capabilities, and ultimately reducing selection accuracy. To overcome such problems, we now apply ‘intelligent’ machine learning tools. Whilst these have achieved success, candidate volumes continue to increase, and our methods have to evolve to keep pace with the change. This talk considers how to meet this challenge as a community.

The analysis of the Ca-K line spectra as a function of latitude and integrated over the visible disk obtained during the period of 1989–2011 at the Kodaikanal Solar Tower Telescope shows that the FWHM of the K1 distribution at different latitudes varies by negligible amount at about 60° latitude whereas it varies significantly at other latitudes. Findings, especially the fewer variations in mid-latitude belts as compared to polar regions and complex variation in the shift in the activity around 60° latitude belt, will have important implications on the modeling of solar dynamos. Further, we have generated a uniform set of digitized Ca-K line images by selecting images considering the intensity distribution of the images corrected for the instrumental vignetting for the data obtained at Kodaikanal during the 20th century. Then, we have determined the percentage of plage and network areas by using the intensity and area threshold values.

The paper presents a proof of concept method of background rejection based on convolutional neural networks (CNN). The method was tested on simulated data and achieved very high accuracy (100%). What is more, method based on CNN is very fast and could be easily applied to wide field surveys. Since early stage results suggest method is very accurate and robust, it could be helpful in creating very low-latency pipelines for EM Follow-up purposes, which will be needed in LIGO-Virgo O3 EM Follow-up.

During the first few ~Myr of a young stars life, it is encircled by a disk made up of molecular gas, dust, and ice – the building blocks for future planetary systems. How/when these disks form planets and what sets the planets initial compositions remain key outstanding questions in disk science. In recent years, major leaps in sensitivity and spatial resolution afforded by the Atacama Large Millimeter/Submillimeter Array (ALMA) have revolutionized our understanding of protoplanetary disks chemical composition and physical properties, revealing in some cases complex radial, vertical, and azimuthal structure in the dust and gas. In this contribution, I review recent observational results and new theoretical puzzles, and how these fit into a newly emerging picture of the disk environment.

The IAU promotes astronomy as a tool to strengthen science education of young people in developing regions through its International Schools for Young Astronomers (ISYA) and a Teaching for Astronomy Development (TAD) programme. This article describes briefly the strategy, organization and development of these programmes. The contents of the courses, tutorials and aims for longer-term effects of these programmes are described with focus on the ISYAs.

We analyze Sun-as-a-star observations spanning over solar cycles 22 – 24 from the ground-based network BiSON and solar cycles 23 – 24 collected by the space-based VIRGO and GOLF instruments on board the SoHO satellite. Using simultaneous observations from all three instruments, our analysis suggests that the structural and magnetic changes responsible for modifying the frequencies remained comparable between cycle 23 and cycle 24 but differ from cycle 22. Thus we infer that the magnetic layer of the Sun has become thinner since the beginning of cycle 23 and continues during the current cycle.

The Galactic halo has a complex assembly history, which can be seen in its wealth of kinematic and chemical substructure. Globular clusters lose stars through tidal interactions with the Galaxy and cluster evaporation processes, meaning that they are inevitably a source of halo stars. These “migrants” from globular clusters can be recognized in the halo field by the characteristic light element abundance anticorrelations that are commonly observed only in globular cluster stars, and the number of halo stars that can be chemically tagged to globular clusters can be used to place limits on the formation pathways of those clusters.

The LIGO/Virgo detections of gravitational waves from merging black holes of ≃ 30 solar mass suggest progenitor stars of low metallicity (Z/Z⊙ ≲ 0.3). In this talk I will provide constrains on where the progenitors of GW150914 and GW170104 may have formed, based on advanced models of galaxy formation and evolution combined with binary population synthesis models. First I will combine estimates of galaxy properties (star-forming gas metallicity, star formation rate and merger rate) across cosmic time to predict the low redshift BBH merger rate as a function of present day host galaxy mass, formation redshift of the progenitor system and different progenitor metallicities. I will show that the signal is dominated by binaries formed at the peak of star formation in massive galaxies with and binaries formed recently in dwarf galaxies. Then, I will present what very high resolution hydrodynamic simulations of different galaxy types can learn us about their black hole populations.

Connecting the observed composition of exoplanets to their formation sites often involves comparing the atmospheric C/O ratio to a disk midplane model with a fixed chemical composition. In this scenario chemistry during the planet formation era is not considered. However, kinetic chemical evolution during the lifetime of the gaseous disk can change the relative abundances of volatile species, thus altering the C/O ratios of planetary building blocks. In our chemical evolition models we utilize a large network of gas-phase, grain-surface and gas-grain interaction reactions, thus providing a comprehensive treatment of chemistry. The results show that, if sufficient ionisation is present, then chemistry does alter the C/O ratios of gas and ice during the epoch of planet(esimal) formation. This modifies the picture of C/O ratios in disk midplanes defined simply by volatile ice lines in a midplane of fixed chemical composition. Chemical evolution thus needs to be addressed when predicting the makeup of planets and their atmospheres.