Research articles

A high-resolution calculation reproducing solar-like differential rotation shows that the strong magnetic field generated by a small-scale dynamo has a substantial impact on thermal convection and is a key step in understanding the 11 yr solar cycle.

The discovery of a multiply imaged, probably of type Ia, supernova in a galaxy at redshift 1.95 enables a time-delay measurement with an uncertainty of <1%. The prediction that a new image will appear in the year 2037 ± 2 allows the use of this system as a cosmological probe.

Rather than cooling down according to a well-established rate, some ~70% of the white dwarfs in globular cluster M13 are delaying their stellar demise by burning left-over hydrogen conserved by skipping the third dredge-up event.

Cosmological hydrodynamical simulations of the ΛCDM Universe show that isolated quenched ultra-diffuse galaxies are formed as backsplash galaxies that were once satellites of another galactic group or cluster halo but are today a few megaparsecs away from them.

An ab initio closed-form analytical solution for the geometric albedo and the integral phase function, which is valid for any law of reflection provided that it depends only on the scattering angle, is proposed. Such solutions can be applied to determine the scattering properties of planetary atmospheres or surfaces.

Chemical inhomogeneities between the two members of a binary star system, where the stars presumably are formed from the same material, could be due to planetary engulfment. Such a fate has befallen planets around a quarter of Sun-like (in temperature and surface gravity) stars, according to this sample of more than 100 binary systems.

Annular (zonally symmetric) atmospheric modes, common on Earth, are found on both Mars and Titan via observations and general circulation models. On Mars, they have considerable impact on dust activity and could be used to predict dust storms. On Titan, they could be linked to sporadic cloud outbursts.

The nearby Ophiuchus star-forming region should be able to give us insight into the incorporation of short-lived radionuclides into the early Solar System. These radionuclides, such as ²⁶Al, originated from multiple sources and gently warmed the protosolar disk over an extended period. Another heating event, therefore—perhaps an FU Orionis-type outburst—presumably led to the resetting of the radiogenic clock.

Like a seismograph, Saturn’s rings are sensitive to oscillations coming from the planet’s interior. State-of-the-art modelling shows that Cassini’s measurements of ring waves point to a convectively stable diffuse core within Saturn, which extends for 60% of its radius and contains 17 Earth masses of ice and rock.

Multi-spacecraft observations of temperature, dust and water ice opacities, water vapour abundances, and thermospheric hydrogen in the atmosphere of Mars during a local dust storm show that even such regional events, much more frequent than global dust storms, can boost global atmospheric escape by a factor of five to ten.

A long-duration campaign to image the Sun’s middle corona—a region about 1.5–3 solar radii from the centre—reveals three dynamical processes that shape and restructure the middle corona. The dynamics can influence the global coronal structure and beyond.

The spectral properties of a short gamma-ray burst indicate that, contrary to expectations, it arose from the collapse of a massive star rather than from a compact binary merger. This discovery also confirms that most collapsars do not produce ultra-relativistic jets.

A gamma-ray burst (GRB) is reported to show a sharp 1-second spike, characteristic of short GRBs, but with other observational properties resembling those of long GRBs. This burst may belong to a class of core-collapse-origin GRBs with genuinely short durations.

Far-UV observations from the Hubble Space Telescope provide evidence of water vapour in the tenuous atmosphere of Ganymede. Atmospheric water originates from surface ice sublimation, with an enrichment in the subsolar region and substantial asymmetry between the leading and trailing hemispheres.

The millimetre image of the Centaurus A nucleus by the Event Horizon Telescope reveals a highly collimated, asymmetrically edge-brightened jet. The source’s event horizon shadow should be visible at terahertz frequencies, consistent with the universal scale invariance of black holes.

Modelling shows that impact gardening on Europa has the potential to churn the shallow subsurface material down to 30 cm very efficiently and globally, thus destroying potential habitable niches just below the surface. Some areas where both gardening and radiation are relatively weak are, however, identified.

Fully three-dimensional magnetohydrodynamic simulations show that solar eruptions can be simply and efficiently initiated in a single bipolar configuration through photospheric shearing motion alone, without the need of any additional special topology.