Articles

Low-frequency quasiperiodic oscillations in X-ray data are thought to trace the accretion flow in X-ray binaries. Here, the detection of 200 keV oscillations probes the innermost regions of MAXI J1820+070, revealing the precession of a small-scale jet.

In situ measurements from the Rosetta spacecraft reveal the presence of atomic emissions close to comet 67P’s nucleus. Such emissions are due to dissociative excitation of molecules by the interaction with the solar wind, identifying them as a form of aurora.

Laboratory spectra of dust/ice aggregates are comparable to those observed in astrophysical environments, questioning the traditional onion-like layered ice model. According to observational spectra, such icy mixtures could harbour water ice in the diffuse interstellar medium, as well as in low-temperature circumstellar environments.

Multi-band high-resolution observations reveal very fast and bursty nanojets. These nanojets are a consequence of the slingshot effect from magnetically tensed, curved magnetic field lines reconnecting at small angles, resulting in coronal heating.

The detection of ~20 ppb of phosphine in Venus clouds by observations in the millimetre-wavelength range from JCMT and ALMA is puzzling, because according to our knowledge of Venus, no phosphine should be there. As the most plausible formation paths do not work, the source could be unknown chemical processes—maybe even life?

Multi-decade observations of Jupiter’s stratospheric temperatures show that their quasiperiodic oscillation locked into a new period after a major atmospheric perturbation in 1992, from 5.7 years to 3.9 years. This is different from Earth (and presumably from Saturn), where the period returned to its original value after substantial atmospheric disruptions.

Far-infrared polarimetric observations reveal a transition parallel to the gas flow in the orientation of magnetic field lines in the Serpens South molecular cloud, allowing gravitational collapse to occur even in the presence of strong magnetic fields.

Spectroscopic data obtained at high spatial resolution from Dawn detected the presence of fresh chloride salts at Cerealia Facula on Ceres. The spatial distribution of the hydration level of these salts suggests that they surfaced a maximum of a few centuries ago and that the upwelling of salty fluids may still be active.

High-spatial-resolution images of the bright points at Occator crater on Ceres, taken during the second extended Dawn mission, allowed reconstruction of the chronology of their formation. The area experienced extensive cryovolcanism less than nine million years ago that lasted several million years, indicating recent geological activity.

An analysis of the relation between a star’s initial mass and its final mass (as a white dwarf) reveals a kink in the initial mass range 1.65–2.10 M_⊙. This kink appears to correspond to the minimum mass required for carbon star formation in the Milky Way at solar metallicity.

Analysis of a catalogue of accreted stars by their radial and prograde motions has identified a 200-plus-member coherent stellar stream (called Nyx) that is likely to be the remnant of a dwarf galaxy that merged with the Milky Way.

Two sources of variability are reported in extreme horizontal branch (EHB) stars found in globular clusters, both related to the action of weak magnetic fields: large surface spots and very energetic flares. EHB stars in clusters can thus be linked to EHB field stars, and beyond, to other stars with radiative envelopes.

Different plasma modes in various Galactic environments are identified on the basis of a synchrotron polarization analysis. These results open up the study of interstellar turbulence and demonstrate its importance in all relevant processes including cosmic ray transport and star formation.

Simulations show that turbulent heating at the solar surface randomly evaporates material to the corona, naturally reproducing the formation of long, fibril-like threads within solar filaments in the solar corona and their counterstreamings.

Without an intrinsic magnetic field, Mars’s magnetosphere is induced by direct interaction between its atmosphere and the solar wind. The mapping of the associated current system, obtained by the MAVEN spacecraft, unveils its convective-driven nature and displays various structural differences compared to Earth.

Galactic close encounters can induce gravitational effects in the participants. Here Ruiz-Lara et al. have reconstructed the star formation history of the region of our Galaxy close to the Sun, finding that three recent visits of the neighbouring Sagittarius dwarf galaxy have resulted in well-defined episodes of star formation.

A zirconium-based crystal (baddeleyite) found embedded in a sample brought to Earth by Apollo 17 provides evidence of large-scale impact bombardment of the Moon about 4.33 Gyr ago, when the baddeleyite grain was formed. This result points to the importance of impacts in the early evolution of planetary crusts.

Escherichia coli bacteria and yeast cultures (representative prokaryotes and eukaryotes) have been tested under laboratory conditions in a 100% H₂ atmosphere. They can reproduce normally, with lower growth rates, producing a range of biosignature gases. Exoplanets with a H₂-dominated atmosphere might thus not be totally hostile to some forms of life.

Methane ice has been presumed to form via the sequential hydrogenation of carbon atoms on dust grains for many years, but now Qasim et al. have performed the experiment, with and without the presence of water. Methane forms more rapidly in the polar ice phase.

Laboratory experiments show that the inclusion of even small quantities of sulfur in the atmospheres of exoplanets at 800 K significantly increases photochemical complexity, both in the vapour and in the solid phase: many sulfur gas products are created (including potential biosignature gases) and the production of organic haze particles increases threefold.