Research articles

Diamonds precipitate from methane under the intense pressures of the atmospheres of Neptune and Uranus. Here, a laser shock experiment on a hydrocarbon sample shows that diamonds may require ten times as much pressure to precipitate as was previously thought.

The stardust component of interstellar dust has been quantified by analysing samples of pre-solar dust grains from meteorites and found to be at least twice as much as had been thought. The silicate portion follows the size distribution of interstellar dust.

Some star clusters in the Large Magellanic Cloud have extended main-sequence turnoffs, suggesting that the component stars have different ages. However, if the blue main-sequence stars were initially spinning rapidly, and experienced braking, the apparent age difference disappears.

M dwarfs harbour stellar dynamos driven by convective motions in their interiors. Previously, the magnetic field strengths generated by these dynamos were thought to saturate at 4 kG, but this limit has now been busted by four stars with dipole dynamo states.

Venus Express wind measurements at Venus’s cloud top during the night show a different picture than dayside. Both fast and slow motions are detected (there are only fast ones during the day) as well as many stationary waves related to surface relief.

Most of the Mars Trojans — asteroids co-orbiting the planet — are dynamically related; thus, they have a common origin. Joint information from spectral observations and dynamical modelling suggests that they were ejected from Mars itself after an impact.

Multiple stars are thought to form either through disk fragmentation or turbulent fragmentation, but the latter has had no clear observational confirmation. Here the authors report misaligned disks around a wide-binary pair, a sign of turbulent fragmentation.

A previously unidentified class of variable stars has been found in OGLE survey data, characterized by periodic brightness variations on ~30-min timescales, amplitudes of ~0.3 mag and temperatures of ~30,000 K. They are potentially evolved low-mass stars.

Combining studies of star formation rates with studies of cloud–magnetic field alignment has revealed that magnetic fields are a primary regulator of star formation. Perpendicular alignment inhibits star formation, whereas parallel alignment facilitates it.

Low-mass black holes that accrete stars from locally dense environments grow over the Hubble time above a minimal mass of 10⁵ solar masses, independently of their initial mass. This explains why there are no convincing cases of intermediate-mass black holes to date.

The brightest galaxy in a cluster is known to align with its host filament in the local Universe. Here this correlation is extended to when the Universe was just a third of its current age. With this, the privileged history of brightest cluster galaxies is reinforced.

Using Si¹⁸O as a velocity tracer, evidence is reported for a rotating outflow driven by a magneto-centrifugal disk wind launched by a high-mass young stellar object. This rotation is a signature of the removal of angular momentum by an outflow.

Disk winds from the surfaces of protoplanetary disks remove angular momentum from radii outside ~10 au. Lee et al. show that residual angular momentum is removed at radii <10 au via highly collimated jets launched at the 0.05 au scale, enabling accretion.

Ultrarelativistic photons and neutrinos from gamma-ray bursts offer a testbed for quantum gravity effects that would lead to an energy dependence of the travel times. A statistical analysis of astrophysical data shows that this behaviour may have been observed.

Coevolving millions of cold dark matter particles and neutrinos within one N-body simulation, TianNu, shows that regions of similar dark matter density can have different neutrino densities. These density variations may have an effect on the cosmic structure.

Gender discrimination is very much an issue in academia generally and in astronomy specifically. Through machine learning techniques, astronomy papers authored by women are shown to have 10% systematically fewer citations than those authored by men.

Oxygen isotope measurements from unequilibrated enstatite chondrites produce a steep slope on a three-isotope plot. This can be explained by the occurrence of silicate–SiO reactions in the early stages of the Solar System’s protoplanetary disk.

Orbital parameters for the seventh Earth-sized transiting planet around star TRAPPIST-1 are reported, along with an investigation into the complex three-body resonances linking every member of this planetary system.

The origin of Galactic positrons that produce gamma ray emission when annihilated is still debated. Mergers of two white dwarfs are likely to be the main source of these positrons. Such mergers produce sub-luminous, thermonuclear supernovae.

Using an innovative method, the mass of a pulsar can be constrained using the maximum ‘glitch’ in the star’s rotational frequency: the bigger the glitch, the lower the mass. This method is used to estimate the mass of all observed glitchers.