Volume 5 Issue 4, April 2021

The largest ever simulation of astrophysical turbulence substantially improves our understanding of how energy injection on large interstellar scales governs how stars form on small scales.

Saturn crossed the orbital resonance that tilted it to its present obliquity of 26.7° only about 1 billion years ago, affected by the fast migration of Titan. The impact of satellite migration on the evolution of giant planet obliquities may be a general phenomenon that could also be relevant for Jupiter and exoplanetary systems.

The Almahata Sitta 202 meteorite fragment hosts evidence of aqueous alteration at intermediate pressures and temperatures, indicative of a hitherto unknown Ceres-sized parent body. Such intermediate conditions, also seen in the Allende meteorite, might have been more common than our biased meteorite collection indicates.

Studies of iron meteorites show that volatile nitrogen originated in three isotopically distinct reservoirs in the early Solar System: the nebular gas, sampled by the Sun and Jupiter, and two others related to organic molecules and dust in the inner and outer Solar System, from which growing protoplanets incorporated nitrogen.

A high-resolution simulation of interstellar turbulence determines the position and width of the transition from supersonic to subsonic turbulence, providing quantitative input for models of filament structure and star formation in molecular clouds.

In April 2020, the Konus-Wind instrument registered two X-ray bursts temporally coincident with two radio bursts from the Galactic magnetar SGR 1935+2154. The unusual spectral hardness of the X-ray bursts may be an indicator of fast-radio-burst-like radio emission from magnetars.

Insight-HXMT detected a double-peaked X-ray burst from Galactic magnetar SGR J1935+2154, consistent with two fast radio bursts (FRBs) observed from the same object within seconds. This coincidence suggests a common physical origin, and gives insight into the mechanism behind the origin of FRBs.

Gigaelectronvolt emission from a magnetar giant flare is discovered by the Fermi Gamma-ray Space Telescope, between 19 s and 284 s after the initial detection of a signal in the megaelectronvolt energy band, potentially generated by an ultra-relativistic outflow far from the stellar magnetosphere.

Stars in the Tucana II ultrafaint dwarf galaxy observed out to nine half-light radii reveal the presence of an extended dark matter halo with a total mass of >10⁷ solar masses, consistent with a generalized Navarro–Frenk–White density profile and suggestive of past strong bursty feedback or an early galactic merger.

In April 2020, the AGILE satellite registered an X-ray burst temporally coincident with a radio burst from the Galactic magnetar SGR 1935+2154. As seen in hard X-rays, the burst was cut off above 80 keV and had an isotropically emitted energy of about 10⁴⁰ erg.

Twenty-four X-ray bursts from a Galactic magnetar simultaneously observed with NICER and Fermi permit a direct comparison to a later X-ray burst that was coincident with a fast radio burst (FRB). The FRB-related burst is spectrally distinct, pointing to an unusual point of emission.

Two further radio bursts associated with magnetar SGR 1935+2154 have been detected with a Westerbork 25 m dish, bringing the total to four. These observations demonstrate that SGR 1935+2154, a putative Galactic analogue of a fast radio burst source, can emit bursts across seven orders of magnitude in energy.