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The detection of a metal-polluted G star in a binary system with an invisible X-ray source offset from the centre of a supernova remnant leads to the suggestion that this was the progenitor pair behind a core-collapse supernova in RCW 86.
The authors put together measurements of ions and neutral atoms from Cassini and the two Voyagers and find that the heliosphere responds quickly (with a lag of 2–3 years) to the solar cycle and that it is bubble-shaped and not tail-shaped, as usually schematized.
Liquid methane lakes dot Titan’s polar regions. Numerical models reveal that the creation of buoyant bubbles through nitrogen exsolution near the bed of the Ligeia Mare lake can explain transient brightenings observed by Cassini on the lake’s surface.
The stacking of nearly three-quarters of a million spectra has unearthed a previously unknown component of the Galactic halo: a widely distributed, neutral, excited hydrogen layer that could harbour a sizeable proportion of the Milky Way’s baryons.
A faint galaxy has been detected in the very early Universe thanks to deep observations and a massive cluster gravitationally magnifying its emission. One out of only five such galaxies known, this detection constrains how the Universe was reionized.
The discovery of several Kuiper belt objects (KBOs) with anomalous properties (they are blue-coloured, whereas KBOs of the same type are red, and they are all binaries) gives constraints on formation processes in the outermost region of the Solar System.
Global-scale Rossby waves develop in planets’ atmospheres and influence their weather. Now, similar waves, driven by magnetism, are unambiguously detected on the Sun. They can possibly help the forecasting of solar activity and related space weather.
Magnetic energy powers explosive flares on the Sun. Now, observations of unprecedented resolution identify the precursors of such flares in the lower solar atmosphere. These findings will help to constrain theoretical models of flare formation.
A bright outburst of activity from the nucleus of comet 67P, observed by Rosetta in July 2015, is traced back to a cliff that partially collapsed at the same time as the outburst, establishing a link between the two events. The collapse has also exposed the fresh ice present under the surface.
The abundance of Be and V isotopes in calcium–aluminium-rich inclusions (CAIs), the oldest solids in the Solar System, shows that CAIs were irradiated by a gradual flux of radiation from solar flares when the Sun was young and more energetic, for a short time (300 yr) and at close distance (≈0.1 au).
Cassini’s RADAR has surveyed a region close to Enceladus’s ‘tiger stripes’. It finds a temperate subsurface with warm cracks, indicating that the moon’s icy crust is only a few kilometres thick at these points. A dormant crack hints at episodic geological activity.
Using asteroseismology to measure the spin axes of stars in two old open star clusters, Corsaro et al. find alignment between significant numbers of stars. It is thought that this is an imprint of the original angular momentum of the parent molecular cloud.
The key ingredients for a massive cloud of gas to collapse and directly form a black hole without fragmenting and forming stars are a strong ionizing background emission and a closely timed burst of star formation in its vicinity.
A magnetohydrodynamic model for outflows around supermassive black holes can also reproduce the X-ray properties of an outflow around a stellar black hole. This indicates that magnetic forces have a universal role to play in driving these winds.
The authors find that a nearby planetary system has two terrestrial planets that transit in front of their star (from our perspective). Transiting terrestrial planets are sought after, as they can be characterized in detail, including their atmospheres. Having two in the same system is very rare.
A selected group of intermediate-redshift galaxies appear similar to primeval galaxies. Analysing spectra of these nearer analogues for chemical abundances and ionization levels gives an improved understanding of galaxies that are too faint to study well.
The roughly spherical outer regions and aspherical inner regions of protoplanetary nebulae — here imaged by ALMA — are explained in terms of an embedded binary system with stars on eccentric orbits.
Environments where stars are abundantly formed are more conducive to stellar tidal disruption events, as evidenced by the detection of the remains of a star being accreted by a supermassive black hole within a starburst galaxy.
A binary system containing a ‘polluted’ white dwarf must host a stable, rocky, circumbinary debris disk, argue Farihi and colleagues. Therefore large planetesimal formation, and potentially terrestrial planet formation, must be robust and common in such systems.
An uncharacteristically long stellar disruption from a supermassive black hole has been unravelling over the last decade. Spectral information implies very efficient accretion but recent observations hint at a transition to a less extreme accretion mode.
