The European Astronomical Society awarded its most prestigious prizes during its annual meeting held from 29 June to 3 July 2020. The meeting was entirely virtual and the largest such gathering of astrophysicists so far.

The determination of the evolutionary stage for a supernova remnant is a demanding task. This guide for radio observers presents a relatively straightforward way to establish the evolutionary phase of newly observed supernova remnants.

The Hayabusa2 and OSIRIS-REx teams have unexpectedly found bright boulders on their respective dark asteroids, Ryugu and Bennu, which provide solid clues about the composition and origin of impacting bodies in their formation history.

Whether ice in cold cosmic environments is physically separated from the silicate dust or mixed with individual silicate moieties is not known. However, different grain models give very different compositions and temperatures of grains. The aim of the present study is to compare the mid-infrared spectra of laboratory silicate grain/water ice mixtures with astronomical observations to evaluate the presence

When rubble-pile asteroid 2008 TC3 impacted Earth on 7 October 2008, the recovered rock fragments indicated that such asteroids can contain exogenic material1,2. However, spacecraft missions to date have only observed exogenous contamination on large, monolithic asteroids that are impervious to collisional disruption3,4. Here, we report the presence of metre-scale exogenic boulders on the surface of

The asteroid (162173) Ryugu and other rubble-pile asteroids are likely re-accumulated fragments of much larger parent bodies that were disrupted by impacts. However, the collisional and orbital pathways from the original parent bodies to subkilometre rubble-pile asteroids are not yet well understood1,2,3. Here we use Hayabusa2 observations to show that some of the bright boulders on the dark, carbonaceous

Low-frequency quasiperiodic oscillations (LFQPOs) are commonly found in black hole X-ray binaries, and their origin is still under debate. The properties of LFQPOs at high energies (above 30 keV) are closely related to the nature of the accretion flow in the innermost regions, and thus play a crucial role in critically testing various theoretical models. The Hard X-ray Modulation Telescope is capable

Having a nucleus darker than charcoal, comets are usually detected from Earth through the emissions from their coma. The coma is an envelope of gas that forms through the sublimation of ices from the nucleus as the comet gets closer to the Sun. In the far-ultraviolet portion of the spectrum, observations of comae have revealed the presence of atomic hydrogen and oxygen emissions. When observed over

About 1 out of 200 Sun-like stars has a planet with an orbital period shorter than one day: an ultrashort-period planet1,2. All of the previously known ultrashort-period planets are either hot Jupiters, with sizes above 10 Earth radii (R⊕), or apparently rocky planets smaller than 2 R⊕. Such lack of planets of intermediate size (the ‘hot Neptune desert’) has been interpreted as the inability of low-mass

The solar corona is shaped and mysteriously heated to millions of degrees by the Sun’s magnetic field. It has long been hypothesized that the heating results from a myriad of tiny magnetic energy outbursts called nanoflares, driven by the fundamental process of magnetic reconnection. Misaligned magnetic field lines can break and reconnect, producing nanoflares in avalanche-like processes. However,

An amendment to this paper has been published and can be accessed via a link at the top of the paper.

LIGO and Virgo’s third observing run revealed the first neutron star–black hole (NSBH) merger candidates in gravitational waves. These events are predicted to synthesize r-process elements1,2 creating optical/near-infrared ‘kilonova’ emission. The joint gravitational wave and electromagnetic detection of an NSBH merger could be used to constrain the equation of state of dense nuclear matter3, and independently

Measurements of trace gases in planetary atmospheres help us explore chemical conditions different to those on Earth. Our nearest neighbour, Venus, has cloud decks that are temperate but hyperacidic. Here we report the apparent presence of phosphine (PH3) gas in Venus’s atmosphere, where any phosphorus should be in oxidized forms. Single-line millimetre-waveband spectral detections (quality up to ~15σ)

Quantitative estimates presented in this issue demonstrate that astronomers contribute more to climate change than the average global citizen. Concerted actions are needed to reduce the ecological impacts of our occupation.

Measuring the carbon emissions of the CFHT in 2019 reveals that the per employee emissions are 16.5 tCO2e, six times above the recommendation of the Paris Agreement, with ~63% due to the electricity consumption of the summit facility and ~25% to out-of-state air travel. Concerted efforts are underway to reduce this figure.

The upper atmospheres of all the giant planets are hotter than models predict. Analysis of Cassini Grand Finale observations of Saturn provide evidence that heat generated by the aurora is responsible.

Analysing greenhouse gas emissions of an astronomical institute is a first step to reducing its environmental impact. Here, we break down the emissions of the Max Planck Institute for Astronomy in Heidelberg and propose measures for reductions.

The annual meeting of the European Astronomical Society took place in Lyon, France, in 2019, but in 2020 it was held online only due the COVID-19 pandemic. The carbon footprint of the virtual meeting was roughly 3,000 times smaller than the face-to-face one, providing encouragement for more ecologically minded conferencing.

Climate change is affecting and will increasingly affect astronomical observations, particularly in terms of dome seeing, surface layer turbulence, atmospheric water vapour content and the wind-driven halo effect in exoplanet direct imaging.

Computer use in astronomy continues to increase, and so also its impact on the environment. To minimize the effects, astronomers should avoid interpreted scripting languages such as Python, and favour the optimal use of energy-efficient workstations.

For astronomers to make a significant contribution to the reduction of climate change-inducing greenhouse gas emissions, we first must quantify the sources of our emissions and review the most effective approaches for reducing them. Here we estimate that Australian astronomers’ total greenhouse gas emissions from their regular work activities are ≳25 ktCO2e yr–1 (equivalent kilotonnes of carbon dioxide

The Pacific Ocean Neutrino Experiment is a new initiative towards constructing a multi-cubic-kilometre neutrino telescope to expand our observable window of the Universe to the highest energies, and will be installed within the deep Pacific Ocean underwater infrastructure of Ocean Networks Canada.

Optical communications will provide the next generation of interplanetary missions with high-bit-rate data transmission, requiring modifications on the ground and in space, explains Leslie Deutsch.

The South Pole–Aitken (SPA) basin is the oldest and largest impact structure on the Moon, and it gives particular insight on the lunar interior composition1,2,3. However, the surface of the SPA basin has been substantially modified by consequent impacts and basalt flooding. The exploration of the surficial material and the substructure of the SPA basin is one of the main scientific goals of the Chinese

The annual Fast Radio Burst conference was held as an entirely virtual event on 6–9 July inclusive, with talks spread over three time zones and an online communication channel for discussions.

A periodic gamma-ray signal detected from the micro-quasar SS 433 cannot be associated with its jet. Instead, a new mechanism capable of channelling most of SS 433’s kinetic power to large distances is needed to explain the observations.

One of the outstanding problems of current observational cosmology is to understand the nature of sources that produced the bulk of the ionizing radiation after the Cosmic Dark Age. Direct detection of these reionization sources1 is practically infeasible at high redshift (z) due to the steep decline of intergalactic medium transmission2,3. However, a number of low-z analogues emitting Lyman continuum

The equatorial stratospheres of Earth, Jupiter and Saturn all exhibit a remarkable periodic oscillation of their temperatures and winds with height. Earth’s quasi-biennial oscillation and Saturn’s quasi-periodic equatorial oscillation have recently been observed to experience disruptions in their vertical structure as a consequence of atmospheric events occurring far from the equator. Here we reveal

A Galactic wind blowing from the Milky Way nucleus has swept up a few hundred clouds of atomic gas. New observations reveal dense molecular cores in two of these clouds, indicating a high loss rate of interstellar gas from the Galactic centre.

An amendment to this paper has been published and can be accessed via a link at the top of the paper.

Far-infrared polarimetric observations reveal the small-scale magnetic field structure within dense gas filaments. Gravity-induced gas flows in filaments supports a scenario in which gravitational collapse and star cluster formation occur even in the presence of relatively strong magnetic fields.

Observations indicate that molecular clouds are strongly magnetized, and that magnetic fields influence the formation of stars. A key observation supporting the conclusion that molecular clouds are significantly magnetized is that the orientation of their internal structure is closely related to that of the magnetic field. At low column densities, the structure aligns parallel with the field, whereas

Microquasars, the local siblings of extragalactic quasars, are binary systems comprising a compact object and a companion star. By accreting matter from their companions, microquasars launch powerful winds and jets, influencing the interstellar environment around them. Steady gamma-ray emission is expected to rise from their central objects, or from interactions between their outflows and the surrounding

During the last 15 years the number of astronomy-related papers published by scientists in Venezuela has been continuously decreasing, mainly due to emigration. If rapid corrective actions are not implemented, professional astronomy in Venezuela could disappear.

Secondary gas disks around main sequence stars may regenerate planetary atmospheres, potentially transforming desiccated rocky worlds into gas-enveloped sub-Neptunes that feature high metallicities and enhanced atmospheric C/O ratios.

Long believed to be a primitive body, Ceres is now an ocean world with deep brines at a regional and potentially global scale. Further studies at Ceres’s conditions and — above all — a follow-up mission are needed to study its evolution and potential habitability.

Before its demise, the Dawn spacecraft performed a series of low passes over the bright spots of dwarf planet Ceres. These high-resolution data highlight the nature of Ceres as an active ocean world with unique characteristics.

The gravity and shape data acquired by the Dawn spacecraft during its primary mission revealed that Ceres is partially differentiated with an interior structure consistent with a volatile-rich crust, a mantle of hydrated rock and isostatically compensated topography1,2,3. Detailed analyses showed that the mechanically strong crust overlays a weak, fluid-bearing upper mantle4. Previous studies, however

The surface and internal structure of Ceres show evidence of a global process of aqueous alteration, indicating the existence of an ocean in the past. However, it is not clear whether part of this ocean is still present and whether residual fluids are still circulating in the dwarf planet. These fluids may be exposed in a geologically young surface, and the most promising site to verify the occurrence

NASA’s Dawn mission revealed a partially differentiated Ceres that has experienced cryovolcanic activity throughout its history up to the recent past. The Occator impact crater, which formed ~22 Myr ago, displays bright deposits (faculae) across its floor whose origins are still under debate: two competing hypotheses involve eruption of brines from the crust–mantle transition boundary (remnants of

Ceres, the only dwarf planet in the inner Solar System, appears to be a relict ocean world. Data collected by NASA’s Dawn spacecraft provided evidence that global aqueous alteration within Ceres resulted in a chemically evolved body that remains volatile-rich1. Recent emplacement of bright deposits sourced from brines attests to Ceres being a persistently geologically active world2,3, but the surprising

The LIGO/Virgo collaboration recently announced the detection of an unusual compact binary merger including either the most massive neutron star or the least massive black hole known. The formation path of such a binary system is still up for debate.

A map of the helium abundance across much of the solar corona will allow us to connect in situ solar wind measurements to their sources and improve our understanding of the origins of the solar wind.

Solar abundances have been historically assumed to be representative of cosmic abundances. However, our knowledge of the solar abundance of helium, the second most abundant element, relies mainly on models1 and indirect measurements through helioseismic observations2, because actual measurements of helium in the solar atmosphere are very scarce. Helium cannot be directly measured in the photosphere

Binary formation is an important aspect of star formation. One possible route for close-in binary formation is disk fragmentation1,2,3. Recent observations show that small-scale asymmetries (<300 au) around young protostars2,4, although not always resolving the circumbinary disk, are linked to disk phenomena5,6. In later stages, resolved circumbinary disk observations7 (<200 au) show similar asymmetries

In the standard model of solar flares, a large-scale reconnection current sheet is postulated to be the central engine for powering the flare energy release1,2,3 and accelerating particles4,5,6. However, where and how the energy release and particle acceleration occur remain unclear owing to the lack of measurements of the magnetic properties of the current sheet. Here we report the measurement of

High angular resolution observations at optical wavelengths provide valuable insights into stellar astrophysics1,2, and enable direct measurements of fundamental stellar parameters3,4 and the probing of stellar atmospheres, circumstellar disks5, the elongation of rapidly rotating stars6 and the pulsations of Cepheid variable stars7. The angular size of most stars is of the order of one milliarcsecond

The practice of peer review has only become commonplace fairly recently, and as such is continually undergoing revision. The latest progress has focused on reducing the load on those performing this community service and also reducing bias to ensure a fairer system for all.

The Emirates will shortly join the ranks of space-faring nations by sending an orbiter to Mars, aiming to make novel observations and inspire the country, write the mission leadership team.

As the Tianwen-1 spacecraft is scheduled for launch in late July or early August, the mission chief scientist and his team provide an overview focusing on the scientific objectives and instrumentation of China’s first Mars mission.

Numerical simulations have predicted that substructures such as spiral arms can be produced through a gravitationally unstable disk around high-mass young stellar objects (HMYSOs)1,2,3,4,5. Recent high-resolution observations from the Atacama Large Millimeter/submillimeter Array have investigated these substructures at a spatial resolution of ~100 au (refs. 6,7,8,9,10). An accretion burst, which is

The initial–final mass relation (IFMR) links the birth mass of a star to the mass of the compact remnant left at its death. While the relevance of the IFMR across astrophysics is universally acknowledged, not all of its fine details have yet been resolved. A new analysis of a few carbon–oxygen white dwarfs in old open clusters of the Milky Way led us to identify a kink in the IFMR, located over a range

The vast majority of stars with mass similar to that of the Sun are expected to destroy lithium (Li) gradually over the course of their lives, via low-temperature nuclear burning. This has now been supported by observations of hundreds of thousands of red giant stars1,2,3,4,5. Here we perform a large-scale systematic investigation into the Li content of stars in the red clump phase of evolution, which

The density structure of the interstellar medium determines where stars form and release energy, momentum and heavy elements, driving galaxy evolution1,2,3,4. Density variations are seeded and amplified by gas motion, but the exact nature of this motion is unknown across spatial scales and galactic environments5. Although dense star-forming gas probably emerges from a combination of instabilities6

Massive dwarf galaxies that merge with the Milky Way on prograde orbits can be dragged into the disk plane before being completely disrupted. Such mergers can contribute to an accreted stellar disk and a dark matter disk. Here we present Nyx, a vast stellar stream in the vicinity of the Sun, which provides the first indication that such an event occurred in the Milky Way. We identify about 200 stars

An amendment to this paper has been published and can be accessed via a link at the top of the paper.

The historic launch of the first several hundred out of 12,000 planned Starlink satellites heralds the arrival of the era of ultra-large satellite constellations. If it will bring new opportunities or insurmountable challenges to astronomy will probably depend on whether you are conducting your observations in space or from the surface of the Earth.

On 3 May 2020 the Greek and extended international astronomy community lost Professor Emeritus John Hugh Seiradakis, a highly impactful, wide-reaching researcher and educator, and mentor to generations of students.

An amendment to this paper has been published and can be accessed via a link at the top of the paper.

An amendment to this paper has been published and can be accessed via a link at the top of the paper.