Research articles

New variability data of the accretion disk in active galactic nuclei argue for the existence of a farther away under-appreciated non-disk component associated with high-density photoionized material that is uplifted from the outer accretion disk.

Using Voyager 1 as a unique probe of the interstellar medium, Lee and Lee have measured the interstellar turbulence spectrum from au scales down to metre scales, complementing the longer wavelength measurements from the scintillation of pulsar emission.

Infrared and neutron spectroscopic observations by Dawn give contrasting results on the elemental composition of Ceres’s surface, which can be reconciled by assuming that Ceres’s surface contains ~20 wt% of carbon, coming from impacts by carbonaceous asteroids and/or generated by extensive aqueous alteration.

Accretion onto the surface of a white dwarf typically generates supersoft X-ray emission and broad emission lines due to nuclear fusion. ASASSN-16oh exhibits no visible broad lines, implying there is no surface fusion, and instead, a belt around the dwarf called a spreading layer is the source of the supersoft X-ray emission.

The largest survey of n = 2,587 professional astronomers reveals regional variations and the drivers behind the most actively engaged communicators.

Moving shadows have been seen on the circumbinary disk around V4046 Sgr, cast by eclipses of the central binary system. Using geometrical arguments, the degree of flaring of the disk and the distance to the system have been calculated.

A state-of-the-art magnetohydrodynamic simulation of a solar flare from emergence to eruption is able to reproduce observations at visible, UV and X-ray wavelengths, and suggests that non-thermal particles at high energy may play a less prominent role than usually assumed in flare models.

Chariklo, Haumea and potentially Chiron are the only known ringed Solar System objects that are not giant planets. The rings of these minor bodies are relatively further from their hosts than those around giant planets; this increase is shown to be due to resonances driven by modest topographic features or elongations.

A model of optical polarization provides a framework for studying the composition and dynamical evolution of the ejecta from the kilonova explosion accompanying the gravitational-wave event GW 170817, as well as future kilonovae.

A serpentine plume of dust around a Wolf–Rayet binary indicates the presence of an anisotropic colliding-wind system in which one of the components is likely to be rapidly rotating. Spun-up Wolf–Rayet stars are thought to be long gamma-ray burst sources.

Information on stellar populations of the grand-design spiral galaxy UGC 3825 is exploited to measure the offset between young stars of a known age and the spiral arm in which they formed. The measured offset is consistent with a quasi-stationary density wave.

A network of parallel ridges on the northwestern border of Sputnik Planitia on Pluto are the traces of debris material deposited by a glaciation of icy nitrogen that happened early in Pluto’s history, and left there once the N₂ ice disappeared by sublimation.

With a lepto-hadronic jet model and recent multi-messenger data, it is shown that a moderate enhancement in cosmic rays during a blazar flare can yield an increased neutrino flux, which is limited by co-produced hard X-rays and TeV gamma rays.

Dust accretion onto a white dwarf follows a broken power-law decay, assuming the dust source is mainly delivered via dynamically falling asteroids perturbed by a Jovian planet. Dust disks are present in the early stage of the metal pollution process.

Direct measurement of stellar rotational velocities in a Galactic open star cluster, combined with a simulation, show that rapidly rotating stars can appear redder, thus broadening the main sequence turn-off. Multiple populations of cluster stars are not required to reproduce the observations.

A convolutional neural network estimates cosmological parameters from simulated weak lensing convergence maps in an unbiased way. The network analysis motivates a new and robust convergence peak-counting algorithm based on the steepness of peak heights.

Using commissioning data from the Australian Square Kilometre Array Pathfinder (ASKAP), parts of the Small Magellanic Cloud (SMC) have been mapped with ten times the resolution of before. Cold H i outflows are found to extend some 2 kpc from the SMC bar, containing up to 3% of the galaxy’s atomic mass. These will probably be stripped by interactions with neighbouring galaxies.

Blue supergiant stars (BSGs) can undergo core collapse, resulting in a type II supernova explosion. Here, Tobias Fischer et al. identify a novel phase transition from nuclear matter to a quark–gluon plasma for particularly massive BSGs (>50 M_☉) that explains their explosion.

A giant protocluster of galaxies at redshift z ≈ 5.7 is found within a large overdense region containing at least 41 spectroscopically confirmed Lyα-emitting galaxies. It will collapse into one of the most massive clusters known to date.

The primordial abundance of helium, set minutes after the Big Bang, is typically measured in star-forming regions in local metal-poor galaxies. Here the helium abundance of an intergalactic gas cloud is calculated using the light of a background quasar instead.