Volume 1

  • No. 12 December 2017

    Optical jet lag

    An artistʼs impression of a black hole accreting matter from a companion star (red) launches a jet of hot plasma (purple), funnelled by swirling magnetic fields. Measurements of a lag between optical and X-ray emission reveal the characteristic elevation where the jet becomes optically thin (white), giving insight into the physics of plasma acceleration.

    See Gandhi et al. 1, 859–864 (2017)

  • No. 11 November 2017

    Nanoflares as coronal heaters

    X-ray measurements of active regions of the Sun, taken by the FOXSI-2 sounding rocket, reveal very energetic X-rays — a signature of hot plasma above 10 million kelvin. As this region does not show any visible flaring activity, the results suggest that nanoflares could be the source of coronal heating.

    See Ishikawa et al. 1, 771–774 (2017).

  • No. 10 October 2017

    Plutoʼs varied terrain

    Pluto displays a remarkable variety of geological processes, many of which are unique. Features captured by New Horizons include jagged mountain peaks abutting both a large putative icy volcanic structure (∼4 km high and 150 km across) and smoother nitrogen ice plains.

    See Olkin et al. 1, 663–670 (2017)

  • No. 9 September 2017

    The Cassini mission has revolutionized our understanding of the Saturn system. This pencil illustration depicts Cassini diving towards Saturn—for one of the last times—as part of the Grand Finale mission. The Cassini mission will end its 20-year odyssey of exploration by plunging into Saturn's atmosphere on September 15th, 2017.

  • No. 8 August 2017

    Star formation in barren and fecund clouds

    A pair of neighbouring molecular clouds, Pipe and Ophiuchus, have similar masses and ages yet very different star formation rates, evident from Ophiuchus’s burst of colour due to stellar feedback. The different birth rates had been a mystery until this study looking into the alignment of the clouds’ structure with their magnetic fields.

    See Li et al. 1, 0158 (2017).

  • No. 7 July 2017

    Spinning bullets from a young gun

    Observations of a narrow, high-velocity jet launched from the innermost regions of a protostar/disk system reveal the presence of spinning clumps of material within the jet. This putative rotation implies that the jet removes angular momentum from the disk, thus allowing disk material to accrete onto the central protostar.

    See Lee et al. 1, 0152 (2017).

  • No. 6 June 2017

    Magnetic meteorology

    A magnetohydrodynamic model shows that wind and weather on HAT-P-7 b, and other very hot extrasolar planets, are affected by its magnetic field. The same model can be used to infer much-needed constraints on the strength of a hot exoplanet's magnetic field, whose lines are represented on the cover.

    See Rogers 1, 0131 (2017).

  • No. 5 May 2017

    Cometary catastrophes

    Rosetta’s cameras captured the collapse of a cliff on the nucleus of comet 67P in near real time, unambiguously connecting it with an outburst of cometary activity.  This landslide also exposed the fresh icy material of the interior of the comet, formed in the cold part of our Solar System roughly 4.5 billion years ago.

    See Pajola et al. 1, 92 (2017).

     

  • No. 4 April 2017

    Imprint of the past

    The discovery of two old open clusters with a substantial number of stars rotating in alignment with each other could represent an imprint of the original angular momentum of the parent molecular cloud from which the stars formed. Our ideas about the turbulent births of stars would suggest that any signature of the momentum should have been wiped out, yet here we have a remnant.

    See Corsaro et al. 1, 0064 (2017).

  • No. 3 1 March 2017

    What lies within

    Evolved stars on the asymptotic giant branch are surrounded by huge envelopes of material that extend a parsec or more. But the structure of these envelopes is dictated by what is happening at the very centre. In this case, an envelope that contains the structure of an Archimedean spiral indicates the presence of an unseen binary star system with eccentric orbits.

    See Kim et al. 1, 0060 (2017).

  • No. 2 February 2017

    Out of the void

    The presence of a galactic void exerting a repelling force on our Local Group of galaxies has been difficult to confirm due to the absence of galaxies. Instead, by measuring the peculiar velocities — velocities in excess of the Universe’s Hubble expansion — of galaxies around the Milky Way, it is possible to reveal that galaxies are flowing away from this 'dipole repeller' and towards a previously known concentration of galaxies called the Great Attractor.

    See Hoffman et al. 1, 0036 (2017).

  • No. 1 January 2017

    Radio rendez-vous

    Radio relics are diffuse radio sources of highly energetic cosmic rays that are found within galaxy clusters. A combined optical, radio (red) and X-ray (blue) study of a colliding pair of galaxy clusters reveals that relativistic electrons ejected from an actively accreting black hole are efficiently re-accelerated at a cluster shock to produce bright, large-scale radio emission.

    See van Weeren et al. 1, 0005 (2017).