Letters in 2019

An intensification of the 7.8-µm methane emission at Jupiter’s poles is observed in coincidence with the arrival of a solar-wind compression in January 2017, highlighting the strong coupling between Jupiter’s magnetosphere and its neutral stratosphere.

High-precision polarization observations of the binary star system Spica reveal that the amount of light from the primary component that is reflected off the secondary component (and vice versa) is a few per cent of the incident light. Such observations will be useful in identifying close binary systems.

There are three different evolutionary pathways leading to post-starburst galaxies in the EAGLE simulations, all consistent with observationally motivated scenarios. These multiple pathways explain the observational diversity of post-starburst galaxies.

Li and Be isotopic measurements of calcium–aluminium inclusions (CAIs) in the Efremovka meteorite suggest that the solid and gaseous precursors of CAIs were irradiated by a superflare during the last stages of the pre-main-sequence evolution of the Sun.

High-angular-resolution observations of 1.3 mm continuum and H30α recombination line emission identify a binary star system in formation, with protostars apparently separated by 180 au. The velocity difference between the two protostars constrains the orbital period and total mass of the system.

Jupiter’s magnetic field can affect the circulation of the internal ocean of Europa and possibly of other Jovian moons by generating a Lorentz force in the ocean’s salty water. Such a force creates an equatorial jet that affects the ocean’s dynamics and acts as a torque on Europa’s ice shell, possibly affecting its surface features.

Farside solar magnetograms are generated from STEREO images using deep learning, with Hale-patterned active regions being well reproduced. These images can be used to monitor the temporal evolution of magnetic fields from the farside to the frontside.

A single gravitational-wave measurement, for example of extreme-mass ratio inspirals by LISA, can be used to verify the existence of light bosons by model selection, rule out alternative explanations for the signal and measure the boson mass.

In this work, more than fifty late-time nebular spectra of stripped-envelope supernovae are studied in order to understand more about the massive-star progenitors of these objects. Type Ib and IIb progenitors are largely indistinguishable; type Ic progenitors likely have more massive carbon–oxygen cores.

Compact exoplanetary systems frequently experience spin–orbit coupling driven by secular resonances, which can shape their architecture, allowing the planet to maintain a large obliquity and inducing the piling up of planets just wide of the first-order resonance.

The decades-old concept of a ‘superwind’ may not apply to extreme oxygen-rich asymptotic giant branch stars since a shell of enhanced circumstellar density (mimicking a superwind) can be produced through binary interaction rather than mass loss.

The initial abundance of ²⁶Al in a planetary system determines the surface environment of its solid planets. High levels of ²⁶Al will dehydrate planetesimals and produce water-poor worlds similar to the terrestrial planets in our Solar System; sub-solar levels of ²⁶Al will preferentially generate ocean planets.

An outburst from young star V883 Ori has vaporized much of the ice inventory of its protoplanetary disk, uniquely revealing a rich organic chemistry involving several complex molecules.

Using precise distances to more than 1,300 classical Cepheids, Chen et al. have traced the warp of the Milky Way’s stellar disk to beyond 20 kpc. The Galaxy’s warp likely arose due to the torques exerted by its massive inner disk.

Kepler-107 b and c have the same radius but, contrary to expectations, the outermost Kepler-107 c is much denser. This difference cannot be explained by photoevaporation by stellar high-energy particle flux and it suggests that Kepler-107 c experienced a giant impact event.

Using a pair of modest telescopes, Arimatsu et al. have observed an occultation event that purports to have been caused by a kilometre-sized Kuiper belt object (KBO). KBOs of this order of magnitude in size have not been detected before, but are likely to represent the most populous size of object in the Kuiper belt.

The distance of outflowing gas from the galaxy centre for 915 quasars is found to be typically tens of parsecs. Typical outflow mass rates and energies indicate that these outflows are energetic enough to influence the evolution of their host galaxies.

The concordance cosmology model is poorly tested at high redshifts. Here the expansion rate of the Universe in the range 0.5 < z < 5.1 is measured based on a Hubble diagram of quasars, whose distances are estimated from their X-ray and ultraviolet emission.

A spatially ubiquitous energy flux from the interior of the Sun reaches the corona through Alfvénic waves generated by internal acoustic modes. Such flux persists for the whole solar cycle and contributes significantly to the energy in the corona.

Using SN 1987A as a cosmic laboratory, Miceli et al. have measured the shock acceleration of ions heavier than oxygen, finding that the post-shock temperature of a wide range of ions is mass dependent.