Coronal mass ejections (CMEs) are tightly related to filament eruptions and usually are their continuation in the upper solar corona. It is common practice to divide all observed CMEs into fast and slow ones. Fast CMEs usually follow eruptive events in active regions near big sunspot groups and associated with major solar flares. Slow CMEs are more related to eruptions of quiescent prominences located far from active regions. We analyse 10 eruptive events with particular attention to the events on 2013 September 29 and on 2016 January 26, one of which was associated with a fast CME, while another was followed by a slow CME. We estimated the initial store of free magnetic energy in the two regions and show the resemblance of pre-eruptive situations. The difference of late behaviour of the two eruptive prominences is a consequence of the different structure of magnetic field above the filaments. We estimated this structure on the basis of potential magnetic field calculations. Analysis of other eight events confirmed that all fast CMEs originate in regions with rapidly changing with height value and direction of coronal magnetic field.

Nowadays, there are several observational studies about the 13CO/C18O abundance ratio ( $X^{13/18}$ ) towards nearby molecular clouds. These works give observational support to the C18O selective photodissociation due to the interaction between the far ultraviolet (FUV) radiation and the molecular gas. It is necessary to increase the sample of molecular clouds located at different distances and affected in different ways by nearby or embedded H ii regions and OB associations to study the selective photodissociation. Using 12CO, 13CO, and C18O J = 1–0 data obtained from the FOREST unbiased Galactic plane imaging survey performed with the Nobeyama 45-m telescope, we analyse the filamentary infrared dark cloud IRDC $34.43+0.24$ located at the distance of about 3.9 kpc. This infrared dark cloud (IRDC) is related to several H ii regions and young stellar objects. Assuming local thermodynamic equilibrium, we obtain: $0.8 \times 10^{16} <$ N(13CO) $<4 \times 10^{17}$ cm–2 (average value $= 4.2 \times 10^{16}$ cm–2), $0.6 \times 10^{15} <$ N(C18O) $<4.4 \times 10^{16}$ cm–2 (average value $= 5.0 \times 10^{15}$ cm–2), and 3 $<$ $X^{13/18}$ $<$ 30 (average $= 8$ ) across the whole IRDC. Larger values of $X^{13/18}$ were found towards portions of the cloud related to the H ii regions associated with the N61 and N62 bubbles and with the photodissociation regions, precisely the regions in which FUV photons are strongly interacting with the molecular gas. Our result represents an observational support to the C18O selectively photodissociation phenomenon occurring in a quite distant filamentary IRDC. Additionally, based on IR data from the Hi-GAL survey, the FUV radiation field was estimated in Habing units, and the dust temperature (T $_{dust}$ ) and H2 column density (N(H2)) distribution were studied. Using the average of N(H2), values in close agreement with the ‘canonical’ abundance ratios [H2]/[13CO] and [H2]/[C18O] were derived. However, the obtained ranges in the abundance ratios show that if an accurate analysis of the molecular gas is required, the use of the ‘canonical’ values may introduce some bias. Thus, it is important to consider how the gas is irradiated by the FUV photons across the molecular cloud. The analysis of $X^{13/18}$ is a good tool to perform that. Effects of beam dilution and clumpiness were studied.

We present VELOCIraptor, a massively parallel galaxy/(sub)halo finder that is also capable of robustly identifying tidally disrupted objects and separate stellar halos from galaxies. The code is written in C++11, use the Message Passing Interface (MPI) and OpenMP Application Programming Interface (API) for parallelisation, and includes python tools to read/manipulate the data products produced. We demonstrate the power of the VELOCIraptor (sub)halo finder, showing how it can identify subhalos deep within the host that have negligible density contrasts to their parent halo. We find a subhalo mass-radial distance dependence: large subhalos with mass ratios of ≳10−2 are more common in the central regions than smaller subhalos, a result of dynamical friction and low tidal mass loss rates. This dependence is completely absent in (sub)halo finders in common use, which generally search for substructure in configuration space, yet is present in codes that track particles belonging to halos as they fall into other halos, such as hbt+. VELOCIraptor largely reproduces the dependence seen without tracking, finding a similar radial dependence to hbt+ in well-resolved halos from our limited resolution fiducial simulation.

We present results of a supernova lightcurve population synthesis, predicting the range of possible supernova lightcurves arising from a population of progenitor stars that include interacting binary systems. We show that the known diversity of supernova lightcurves can be interpreted as arising from binary interactions. Given detailed models of the progenitor stars, we are able to the determine what parameters within these stars determine the shape of their supernova lightcurve. The primary factors are the mass of supernova ejecta and the mass of hydrogen in the final progenitor. We find that there is a continuum of lightcurve behaviour from type IIP, IIL, to IIb supernovae related to the range of hydrogen and ejecta masses. Most type IIb supernovae arise from a relatively narrow range of initial masses from 10 to 15 M⊙. We also find a few distinct lightcurves that are the result of stellar mergers.

GravityCam is a new concept of ground-based imaging instrument capable of delivering significantly sharper images from the ground than is normally possible without adaptive optics. Advances in optical and near-infrared imaging technologies allow images to be acquired at high speed without significant noise penalty. Aligning these images before they are combined can yield a 2.5–3-fold improvement in image resolution. By using arrays of such detectors, survey fields may be as wide as the telescope optics allows. Consequently, GravityCam enables both wide-field high-resolution imaging and high-speed photometry. We describe the instrument and detail its application to provide demographics of planets and satellites down to Lunar mass (or even below) across the Milky Way. GravityCam is also suited to improve the quality of weak shear studies of dark matter distribution in distant clusters of galaxies and multiwavelength follow-ups of background sources that are strongly lensed by galaxy clusters. The photometric data arising from an extensive microlensing survey will also be useful for asteroseismology studies, while GravityCam can be used to monitor fast multiwavelength flaring in accreting compact objects and promises to generate a unique data set on the population of the Kuiper belt and possibly the Oort cloud.

With the recent discovery of a dozen dusty star-forming galaxies and around 30 quasars at z > 5 that are hyper-luminous in the infrared (μ LIR > 1013 L⊙, where μ is a lensing magnification factor), the possibility has opened up for SPICA, the proposed ESA M5 mid-/far-infrared mission, to extend its spectroscopic studies toward the epoch of reionisation and beyond. In this paper, we examine the feasibility and scientific potential of such observations with SPICA’s far-infrared spectrometer SAFARI, which will probe a spectral range (35–230 μm) that will be unexplored by ALMA and JWST. Our simulations show that SAFARI is capable of delivering good-quality spectra for hyper-luminous infrared galaxies at z = 5 − 10, allowing us to sample spectral features in the rest-frame mid-infrared and to investigate a host of key scientific issues, such as the relative importance of star formation versus AGN, the hardness of the radiation field, the level of chemical enrichment, and the properties of the molecular gas. From a broader perspective, SAFARI offers the potential to open up a new frontier in the study of the early Universe, providing access to uniquely powerful spectral features for probing first-generation objects, such as the key cooling lines of low-metallicity or metal-free forming galaxies (fine-structure and H2 lines) and emission features of solid compounds freshly synthesised by Population III supernovae. Ultimately, SAFARI’s ability to explore the high-redshift Universe will be determined by the availability of sufficiently bright targets (whether intrinsically luminous or gravitationally lensed). With its launch expected around 2030, SPICA is ideally positioned to take full advantage of upcoming wide-field surveys such as LSST, SKA, Euclid, and WFIRST, which are likely to provide extraordinary targets for SAFARI.

Molecular line intensity calculations are not a straightforward task. We present a description of the basics for including molecular lines in synthetic spectra and of the input data needed. We aim both at describing ways in which molecular lines are computed in the context of photospheres of F–G–K stars, and to present a new online available version of our code for spectrum synthesis of cool stars. We apply calculations to molecular bands in the ultraviolet, visible, and near-infrared main features, and comparisons with spectra of reference stars are shown. We provide user-friendly tools for the free use of the code Pfant. The code is available at http://trevisanj.github.io/PFANT.

We provide the first in situ measurements of antenna element beam shapes of the Murchison Widefield Array. Most current processing pipelines use an assumed beam shape, which can cause absolute and relative flux density errors and polarisation ‘leakage’. Understanding the primary beam is then of paramount importance, especially for sensitive experiments such as a measurement of the 21-cm line from the epoch of reionisation, where the calibration requirements are so extreme that tile to tile beam variations may affect our ability to make a detection. Measuring the primary beam shape from visibilities is challenging, as multiple instrumental, atmospheric, and astrophysical factors contribute to uncertainties in the data. Building on the methods of Neben et al. [Radio Sci., 50, 614], we tap directly into the receiving elements of the telescope before any digitisation or correlation of the signal. Using ORBCOMM satellite passes we are able to produce all-sky maps for four separate tiles in the XX polarisation. We find good agreement with the beam model of Sokolowski et al. [2017, PASA, 34, e062], and clearly observe the effects of a missing dipole from a tile in one of our beam maps. We end by motivating and outlining additional on-site experiments.

For core-collapse and neutron star merger simulations, it is important to have adequate equations of state which describe dense and hot matter as realistically as possible. We present two newly constructed equations of state including the entire baryon octet, compatible with the main constraints coming from nuclear physics, both experimental and theoretical. One of the equations of state describes cold β-equilibrated neutron stars with a maximum mass of 2 Msun. Results obtained with the new equations of state are compared with the ones of DD2Y, the only existing equation of state containing the baryon octet and satisfying the above constraints. The main difference between our new equations of state and DD2Y is the harder symmetry energy of the latter. We show that the density dependence of the symmetry energy has a direct influence on the amount of strangeness inside hot and dense matter and, consequently, on thermodynamic quantities. We expect that these differences affect the evolution of a proto-neutron star or binary neutron star mergers. We propose also several parameterisations based on the DD2 and SFHo models calibrated to Lambda hypernuclei that satisfy the different constraints.

The low-frequency polarisation properties of radio sources are poorly studied, particularly in statistical samples. However, the new generation of low-frequency telescopes, such as the Murchison Widefield Array (the precursor for the low-frequency component of the Square Kilometre Array) offers an opportunity to probe the physics of radio sources at very low radio frequencies. In this paper, we present a catalogue of linearly polarised sources detected at 216 MHz, using data from the Galactic and Extragalactic All-sky Murchison Widefield Array survey. Our catalogue covers the Declination range –17° to –37° and 24 h in Right Ascension, at a resolution of around 3 arcminutes. We detect 81 sources (including both a known pulsar and a new pulsar candidate) with linearly polarised flux densities in excess of 18 mJy across a survey area of approximately 6 400 deg2, corresponding to a surface density of 1 source per 79 deg2. The level of Faraday rotation measured for our sources is broadly consistent with those recovered at higher frequencies, with typically more than an order of magnitude improvement in the uncertainty compared to higher-frequency measurements. However, our catalogue is likely incomplete at low Faraday rotation measures, due to our practice of excluding sources in the region where instrumental leakage appears. The majority of sources exhibit significant depolarisation compared to higher frequencies; however, a small sub-sample repolarise at 216 MHz. We also discuss the polarisation properties of four nearby, large-angular-scale radio galaxies, with a particular focus on the giant radio galaxy ESO 422–G028, in order to explain the striking differences in polarised morphology between 216 MHz and 1.4 GHz.

We adopt two- and three-body nuclear forces derived at the next-to-next-to-leading-order in the framework of effective chiral perturbation theory to calculate the equation of state of β-stable neutron star matter using the Brueckner–Hartree–Fock many-body approach. We use the recent optimized chiral two-body nuclear interaction at next-to-next-to-leading-order derived by Ekström et al. and two different parametrizations of the three-body next-to-next-to-leading-order interaction: the first one is fixed to reproduce the saturation point of symmetric nuclear matter while the second one is fixed to reproduce the binding energies of light atomic nuclei. We show that in the second case the properties of nuclear matter are not well determined whereas in the first case various empirical nuclear matter properties around the saturation density are well reproduced. We finally calculate various neutron star properties and in particular the mass-radius and mass-central density relations. We find that the adopted interactions based on a fully microscopic framework, are able to provide an equation of state which is consistent with the present data of measured neutron star masses.

In 1918 the only Mexican institution dedicated professionally to astronomical work was the National Astronomical Observatory, which had begun operations in 1878. In that year of the 20th century, Mexico was immersed in the armed movement known as the Mexican Revolution, which strongly affected the social and economic structure of the country. The Mexican astronomers saw their group drastically reduced and their infrastructure limited; however, they made great efforts to continue their participation in the international project of the Carte du Ciel, since they were part of the 18 observatories that originally participated in it. Despite the limitations they suffered, they soon joined the group of seven nations that in 1919 formed the IAU, and two members of that observatory actively participated in the first general assembly held in Rome in May 1922.

The Night-Sky Observation Program (POC, acronym in Portuguese for Programa de Observação do Céu) is the most traditional education activity run by the Museum of Astronomy and Related Sciences (MAST), located in Rio de Janeiro, Brazil. The activity starts with a brief talk about the astronomical objects available for visibility and is followed by the sky observation with MAST’s telescopes, one of them being over a century old. A study conducted in 2015 pointed out that its participants perceive the historical value of the old refractor and declare that the activity brings them feelings of wonderment. These perceptions and declarations have motivated us to conduct a new study to identify and exchange experiences with institutions worldwide that also use historically valuable telescopes in their night-sky observation activities with the public. With the goal of gathering information from these institutions and making it into a guide, an online survey with open and close-ended questions was launched in late 2017. Nearly eighty institutions from all continents answered our questionnaire. The data collected are vast and rich and not only tell about the passion of those mediating such activities, but also the history of astronomy itself.

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.

Can we make a copy of Tycho’s “De Nova Stella” that can in fact survive a nova? At first, this may seem at best a nerdish, if not distinctly foolish question. However, it is also both a technological and a philosophical question: in fact, answering questions like this is linked to both technical, physical and sociological problems related to the long-term preservation and curation of objects from current and past civilizations.

The undertaking presented here is two-fold: Firstly, we report on the results from a state-of the art short-term project, in which we have digitized and analysed three well-known rare books Pertain ing to astronomical observations by Tycho Brahe on the island of Hven. The project led to the creation of free e-books, enabling open access to the sky as recorded by Tycho.

Secondly, we discuss some long-term issues related to the digital and physical preservation of scientific knowledge and heritage in general, exemplified by e.g. the works by Tycho.

Future work includes further physical analysis of the books and fragments, a systematic extraction and digitization of the astronomical observations, digital curation and dissemination, as well as research into the possibility of creating representations and replicas of the works, durable on extremely long time-scales.

At the Sydney IAU General Assembly (GA) the statutes were modified to remove the votes by individual members. Few noticed this at the time but the subsequent reaction by disenfranchised members led us to revise this position in Prague. The need to have a members’ vote on the status of Pluto was complicated by these changes and the drama behind the scene at the Prague GA where the planet definition was resolved is not well known despite the huge public impact of this GA. I will describe some of the activities of the executive and its working groups during this very exciting GA. The IAU structures served us well during this process but of course there were also many lessons learned.