The CONCERTO instrument paves the way to large field-of-view spectro-imagers operating at (sub-)millimetre wavelengths, write Instrument Scientist Alessandro Monfardini and Principal Investigator Guilaine Lagache.

Astronomers are used to advocating for (financial) support for their future endeavours, but how should they go about lobbying for support for issues such as the climate emergency? Join forces with those experienced in effecting policy change.

The standard model of terrestrial planet formation ignores the role of orbital migration of planetary embryos. A new scenario shows how migration may have sculpted the inner Solar System’s orbital architecture, as long as embryos converged towards about 1 au.

Astronomers are trusted voices in the communication of science; our community should resist inundating people with facts and figures but use its advantage to encourage the public to listen to climate change experts and encourage the need for urgent cross-sectoral systemic change.

As the world recovers from one global crisis, it must steel itself for the coming of a far greater one: the climate crisis. Astronomers and planetary scientists have roles to play as trusted scientific experts, but should seek partnerships with domain experts when venturing outside their areas of knowledge.

When do we stop an ongoing science project to make room for something new? Decision-making is a complex process, ranging from budgetary considerations and tension between ongoing projects, to progress assessments and allowance for novel science developments.

The climate crisis is no longer a prediction for the future, it is happening here and now. Astronomers have realized that they need to become part of the solution and are working towards reducing their own carbon footprint as well as communicating an astronomical perspective.

Gravitational wave (GW) detection in space probes the GW spectrum that is inaccessible from the Earth. In addition to the LISA project led by the European Space Agency, and the DECIGO detector proposed by the Japan Aerospace Exploration Agency, two Chinese space-based GW observatories—TianQin and Taiji—are planned to be launched in the 2030s. TianQin has a unique concept in its design with a geocentric

A supernova, possibly of type Ia, gravitationally lensed by a massive cluster, is predicted to appear in the future. It has the potential to allow an independent, high-precision measurement of the Hubble constant.

The Sun rotates differentially with a fast equator and slow pole1. Convection in the solar interior is thought to maintain the differential rotation. However, although many numerical simulations have been conducted to reproduce the solar differential rotation2,3,4,5,6,7, previous high-resolution calculations with solar parameters fall into the antisolar (fast-pole) differential rotation regime. Consequently

When the light from a distant object passes very near to a foreground galaxy or cluster, gravitational lensing can cause it to appear as multiple images on the sky1. If the source is variable, it can be used to constrain the cosmic expansion rate2 and dark energy models3. Achieving these cosmological goals requires many lensed transients with precise time-delay measurements4. Lensed supernovae are

Ultra-light dark matter is a class of dark matter models (DM), where DM is composed by bosons with masses ranging from \(10^{-24}\, \mathrm {eV}< m < \mathrm {eV}\). These models have been receiving a lot of attention in the past few years given their interesting property of forming a Bose–Einstein condensate (BEC) or a superfluid on galactic scales. BEC and superfluidity are some of the most striking

White dwarfs (WDs) are the final evolutionary product of the vast majority of stars in the Universe. They are electron-degenerate structures characterized by no stable thermonuclear activity, and their evolution is generally described as a pure cooling process. Their cooling rate is adopted as cosmic chronometer to constrain the age of several Galactic populations, including the disk, globular and

Ultra-diffuse galaxies (UDGs) are the lowest-surface-brightness galaxies known, with typical stellar masses of dwarf galaxies but sizes similar to those of larger galaxies such as the Milky Way1. The reason for their extended sizes is debated, with suggested internal processes such as angular momentum2, feedback3,4 or mergers5 versus external mechanisms6,7,8,9 or a combination of both10. Observationally

Much of the progress in astronomy has been driven by instrumental developments, from the first telescopes to fiber fed spectrographs. In this review, we describe the field of astrophotonics, a combination of photonics and astronomical instrumentation that is gaining importance in the development of current and future instrumentation. We begin with the science cases that have been identified as possibly

Studying the albedos of the planets and moons of the Solar System dates back at least a century1,2,3,4. Of particular interest is the relationship between the albedo measured at superior conjunction, known as the ‘geometric albedo’, and the albedo considered over all orbital phase angles, known as the ‘spherical albedo’2,5,6. Determining the relationship between the geometric and spherical albedos

Stellar members of binary systems are formed from the same material, and therefore they should be chemically identical. However, recent studies have unveiled chemical differences between the two members of binary pairs composed of Sun-like stars. These chemically inhomogeneous binaries represent one of the most contradictory examples in stellar astrophysics and a source of tension between theory and

Annular modes explain much of the internal variability of Earth’s atmosphere but have never been identified as influential on other planets. Using data assimilation datasets for Mars and a general circulation model for Titan, we demonstrate that annular modes are prominent in the atmospheres of both worlds, capturing a larger fraction of their respective variabilities than Earth’s. One mode describes

In this review, I will discuss the comparison between model results and observational data for the Milky Way, the predictive power of such models as well as their limits. Such a comparison, known as Galactic archaeology, allows us to impose constraints on stellar nucleosynthesis and timescales of formation of the various Galactic components (halo, bulge, thick disk and thin disk).

The European Astronomical Society awarded its most prestigious prizes during its annual meeting held from 28 June to 2 July 2021. In a way similar to last year, the meeting was entirely virtual.

Our view of fast radio bursts — millisecond duration pulses of high intensity — has gained significant clarity following the discovery of hundreds of sources that are helping us to understand the nature of this enigmatic phenomenon.

Anomalies among the daughter nuclei of the extinct short-lived radionuclides in calcium–aluminium-rich inclusions indicate that the Solar System must have been born near a source of the short-lived radionuclides so that they could be incorporated before they decayed away1. γ-rays from one such living short-lived radionuclide, 26Al, are detected in only a few nearby star-forming regions. Here we employ

The best constraints on the internal structures of giant planets have historically originated from measurements of their gravity fields1,2,3. These data are inherently mostly sensitive to a planet’s outer regions, stymieing efforts to measure the mass and compactness of the cores of Jupiter2,4,5 and Saturn6,7. However, studies of Saturn’s rings have detected waves driven by pulsation modes within the

Mars has lost most of its initial water to space as atomic hydrogen and oxygen. Spacecraft measurements have determined that present-day hydrogen escape undergoes large variations with season that are inconsistent with long-standing explanations. The cause is incompletely understood, with likely contributions from seasonal changes in atmospheric circulation, dust activity and solar extreme ultraviolet

Many people have been unable to travel due to the pandemic, or even take a ‘staycation’. This August, we encourage you to slow down, look after your mental health, and let these stunning photographs transport you to a different place.

The measured blue and redshifts of galaxies within filaments in the local Universe are consistent with the large-scale flow of matter within walls, but they may also point to evidence for their rotation.

After five years of construction, the Large High Altitude Air Shower Observatory is nearing completion, but already returning exciting results on the origin of cosmic rays, explains Principal Investigator Zhen Cao.

The missing baryon problem may now be resolved, but the exact location and physical properties of the diffuse component remains unclear. This problem could be tractable, but requires a combination of new galaxy redshift surveys and new X-ray and radio facilities.

Identifying the sources of high-energy cosmic neutrinos has been a challenge. Considering frequentist and Bayesian arguments, as well as the special conditions found in neutrino astronomy, we discuss whether to believe current 3σ observations.

The ‘middle corona’ is a critical transition between the highly disparate physical regimes of the lower and outer solar coronae. Nonetheless, it remains poorly understood due to the difficulty of observing this faint region (1.5–3 R☉). New observations from the Solar Ultraviolet Imager of a Geostationary Operational Environmental Satellite in August and September 2018 provide the first comprehensive

The association of a short gamma-ray burst with a core-collapse supernova seems to challenge current scenarios for the origin of these extreme events. But how much can we rely on observed duration for pinpointing their progenitors?

Gamma-ray bursts (GRBs) are among the brightest and most energetic events in the Universe. The duration and hardness distribution of GRBs has two clusters1, now understood to reflect (at least) two different progenitors2. Short-hard GRBs (SGRBs; T90 < 2 s) arise from compact binary mergers, and long-soft GRBs (LGRBs; T90 > 2 s) have been attributed to the collapse of peculiar massive stars (collapsars)3

Gamma-ray bursts (GRBs) have been phenomenologically classified into long and short populations based on the observed bimodal distribution of duration1. Multi-wavelength and multi-messenger observations in recent years have revealed that in general long GRBs originate from massive star core collapse events2, whereas short GRBs originate from binary neutron star mergers3. It has been known that the

While most of the compact-binary mergers detected by LIGO and Virgo are expected to consist of first-generation black holes formed from the collapse of stars, others might instead be of second (or higher) generation, containing the remnants of previous black-hole mergers. We review theoretical findings, astrophysical modelling and current gravitational-wave evidence of hierarchical stellar-mass black-hole

Ganymede’s atmosphere is produced by charged particle sputtering and sublimation of its icy surface. Previous far-ultraviolet observations of the O i 1,356 Å and O i 1,304 Å oxygen emissions were used to infer sputtered molecular oxygen (O2) as an atmospheric constituent, but an expected sublimated water (H2O) component remained undetected. Here we present an analysis of high-sensitivity spectra and

New extremely high-resolution observations of the radio jets of the active galaxy Centaurus A have revealed striking brightening at the jet edges. This may be a common feature of jet outflows from active galaxies, but its origin remains unclear.

Very-long-baseline interferometry (VLBI) observations of active galactic nuclei at millimetre wavelengths have the power to reveal the launching and initial collimation region of extragalactic radio jets, down to 10–100 gravitational radii (rg ≡ GM/c2) scales in nearby sources1. Centaurus A is the closest radio-loud source to Earth2. It bridges the gap in mass and accretion rate between the supermassive

After years of relative neglect, Venus is enjoying renewed interest, with several missions bound to reach it in the next decade. Many questions about its nature still need to be answered, including regarding the highly debated presence of phosphine.

The Keck Planet Imager and Characterizer develops the Keck II telescope’s adaptive optics and instrument systems to enable infrared imaging and spectroscopy of gas giant exoplanets, explains Principal Investigator Dimitri Mawet.

The behaviour of minerals under high pressure affects the bulk properties of exoplanets and planets with rocky components, possibly influencing their observable radii. Obtaining a wide range of experimental data is key to understanding observations and informing planetary interior models.

By focusing on the topic of stellar dynamics and stellar populations of the Milky Way and its siblings, a recent virtual meeting aimed at connecting both fields, each of which brings unique perspectives to understanding how disk galaxies form and evolve.

Turmoil has engulfed the solar community for decades about which physical mechanisms are sufficient to trigger and drive solar eruptions. New high-resolution numerical magnetohydrodynamic simulations bring an old idea back into the light: the reconnection jet from the tether-cutting model.

Novel observational evidence appears to confirm that when mass is supplied to massive black holes at low rates, only a fraction is actually accreted. Much of the gas may be lost in a low-speed magnetohydrodynamic wind.

Owing to its internal ocean, Jupiter’s moon Europa can potentially host extant life. However, because Europa’s orbit is within Jupiter’s magnetosphere, chemical biosignatures that are exposed to space may be destroyed by high-energy electron radiation. It has been suggested that biosignatures may be preserved below the radiation-penetration depth of the top few centimetres. Impact gardening, the process

Solar eruptions are spectacular magnetic explosions in the Sun’s corona, and how they are initiated remains unclear. Prevailing theories often rely on special magnetic topologies that may not generally exist in the pre-eruption source region of corona. Here, using fully three-dimensional magnetohydrodynamic simulations with high accuracy, we show that solar eruptions can be initiated in a single bipolar

Photochemical hazes are important opacity sources in temperate exoplanet atmospheres, hindering current observations from characterizing exoplanet atmospheric compositions. The haziness of an atmosphere is determined by the balance between haze production and removal. However, the material-dependent removal physics of the haze particles are currently unknown under exoplanetary conditions. Here we provide

For most of their lifetime, super-massive black holes (SMBHs) commonly found in galactic nuclei obtain mass from the ambient medium at a rate well below the Eddington limit1, which is mediated by a radiatively inefficient, hot accretion flow2. Both theory and numerical simulations predict that a strong wind must exist in such hot accretion flows3,4,5,6. The wind is of special interest not only because

Supernovae Ia are bright explosive events that can be used to estimate cosmological distances, allowing us to study the expansion of the Universe. They are understood to result from a thermonuclear detonation in a white dwarf that formed from the exhausted core of a star more massive than the Sun. However, the possible progenitor channels leading to an explosion are a long-standing debate, limiting

The fate of galaxies is predominantly determined by their dark matter halo mass. However, recent simulations confirm an important role for the formation history, revealing an intricate relation between galaxies’ central supermassive black holes and the colours of their hosts.

The massive cores of the giant planets are thought to have formed in a gas disk by the accretion of pebble-sized particles whose accretional cross-section was enhanced by aerodynamic gas drag1,2. A commonly held view is that the terrestrial planet system formed later (30–200 Myr after the dispersal of the gas disk) by giant collisions of tens of lunar- to Mars-sized protoplanets3,4. Here we propose

The development of reusable artificial intelligence (AI) models for wider use and rigorous validation by the community promises to unlock new opportunities in multi-messenger astrophysics. Here we develop a workflow that connects the Data and Learning Hub for Science, a repository for publishing AI models, with the Hardware-Accelerated Learning (HAL) cluster, using funcX as a universal distributed

Palomar 5 is one of the sparsest star clusters in the Galactic halo and is best known for its spectacular tidal tails, spanning over 20° across the sky. With N-body simulations, we show that both distinguishing features can result from a stellar-mass black hole population, comprising ~20% of the present-day cluster mass. In this scenario, Palomar 5 formed with a ‘normal’ black hole mass fraction of

Recent observations reveal that, at a given stellar mass, blue galaxies tend to live in haloes with lower mass, while red galaxies live in more massive host haloes. The physical driver behind this is still unclear because theoretical models predict that, at the same halo mass, galaxies with high stellar masses tend to live in early-formed haloes, which naively leads to the opposite trend. Here, we

Observations from the brand-new CHEOPS mission reveal a third long-period transiting planet around the naked-eye star ν2 Lupi. Precise measurements of the masses and radii of planets around this star show a diversity of planetary compositions possibly ranging from bare rock to a significant volatile atmosphere.

Exoplanets transiting bright nearby stars are key objects for advancing our knowledge of planetary formation and evolution. The wealth of photons from the host star gives detailed access to the atmospheric, interior and orbital properties of the planetary companions. ν2 Lupi (HD 136352) is a naked-eye (V = 5.78) Sun-like star that was discovered to host three low-mass planets with orbital periods of

In the transitional mass range (~8–10 solar masses) between white dwarf formation and iron core-collapse supernovae, stars are expected to produce an electron-capture supernova. Theoretically, these progenitors are thought to be super-asymptotic giant branch stars with a degenerate O + Ne + Mg core, and electron capture onto Ne and Mg nuclei should initiate core collapse1,2,3,4. However, no supernovae

The recent suggestion of phosphine in Venus’s atmosphere has regenerated interest in the idea of life in clouds. However, such analyses usually neglect the role of water activity, which is a measure of the relative availability of water, in habitability. Here we compute the water activity within the clouds of Venus and other Solar System planets from observations of temperature and water-vapour abundance

In situ investigations by the Mars Science Laboratory Curiosity rover have confirmed the presence of an ancient lake that existed in Gale crater for up to 10 million years. The lake was filled with sediments that eventually converted to a compacted sandstone. However, it remains unclear whether the infilling of the lake was the result of background sedimentation processes or represents punctual flooding

The current Martian atmosphere is about five times more enriched in deuterium than Earth’s, providing direct testimony that Mars hosted vastly more water in its early youth than nowadays. Estimates of the total amount of water lost to space from the current mean D/H value depend on a rigorous appraisal of the relative escape between deuterated and non-deuterated water. Isotopic fractionation of D/H

The short lifespan of software puts a time limit on the reproducibility of computational research. To extend software longevity, guidelines and tools to preserve scientific workflows and analysis are helpful, but the challenge is to get researchers to use them.