Volume 3 Issue 5, May 2019

The PLOAD — Portuguese Language Office of Astronomy for Development — was established in 2015 by the International Astronomical Union (IAU) with the goal of promoting astronomy as a tool for sustainable development in Portuguese-speaking countries.

South Africa is looking forward to hosting the IAU General Assembly in 2024 — the first on the African continent. The meeting will come at a time of burgeoning scientific prosperity for the growing community of indigenous South African and African astronomers.

Do black holes rotate, and if yes, how fast? This question is fundamental and has broad implications, but still remains open. There are significant observational challenges in current spin determinations, but future facilities offer prospects for precision measurements.

After 30 years of searching, the helium hydride ion, the first chemical bond that was formed in the Universe, has finally been detected outside the laboratory, in the interstellar medium. It was seen in planetary nebula NGC 7027 using the GREAT spectrometer aboard the Stratospheric Observatory for Infrared Astronomy.

While the measurements of the Hubble constant from the local distance ladder and the cosmic microwave background radiation appear to disagree, given a sufficient number of localized detections, gravitational waves may possibly shed light on the tension.

This article reviews radio emission mechanisms in radio-quiet active galactic nuclei (AGNs), from star formation and AGN winds, to free-free emission from photoionized gas and AGN disk coronal activity. These mechanisms can be probed by sensitive radio observatories.

Farside solar magnetograms are generated from STEREO images using deep learning, with Hale-patterned active regions being well reproduced. These images can be used to monitor the temporal evolution of magnetic fields from the farside to the frontside.

Jupiter’s magnetic field can affect the circulation of the internal ocean of Europa and possibly of other Jovian moons by generating a Lorentz force in the ocean’s salty water. Such a force creates an equatorial jet that affects the ocean’s dynamics and acts as a torque on Europa’s ice shell, possibly affecting its surface features.

The decades-old concept of a ‘superwind’ may not apply to extreme oxygen-rich asymptotic giant branch stars since a shell of enhanced circumstellar density (mimicking a superwind) can be produced through binary interaction rather than mass loss.

Kepler-107 b and c have the same radius but, contrary to expectations, the outermost Kepler-107 c is much denser. This difference cannot be explained by photoevaporation by stellar high-energy particle flux and it suggests that Kepler-107 c experienced a giant impact event.

Compact exoplanetary systems frequently experience spin–orbit coupling driven by secular resonances, which can shape their architecture, allowing the planet to maintain a large obliquity and inducing the piling up of planets just wide of the first-order resonance.

In this work, more than fifty late-time nebular spectra of stripped-envelope supernovae are studied in order to understand more about the massive-star progenitors of these objects. Type Ib and IIb progenitors are largely indistinguishable; type Ic progenitors likely have more massive carbon–oxygen cores.

There are three different evolutionary pathways leading to post-starburst galaxies in the EAGLE simulations, all consistent with observationally motivated scenarios. These multiple pathways explain the observational diversity of post-starburst galaxies.

A single gravitational-wave measurement, for example of extreme-mass ratio inspirals by LISA, can be used to verify the existence of light bosons by model selection, rule out alternative explanations for the signal and measure the boson mass.

LOFAR radio observations, complemented by ultraviolet and visible light images, of the powerful class-X8.2 solar flare of 10 September 2017 pinpoint the location of multiple shock signatures of electron beams (herringbones) along the expanding coronal mass ejection.

SCExAO is an instrument on the Subaru Telescope that is pushing the frontiers of what is possible with ground-based direct imaging of terrestrial exoplanets, explains Thayne Currie, on behalf of the SCExAO team.