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  • An image-template analysis of eight years of Fermi-LAT data shows that the anomalous emission of gigaelectronvolt energies close to the centre of our Galaxy is better fitted with a boxy-shaped bulge generated by stars — possibly millisecond pulsars — than with a dark matter signal.

    • Richard Bartels
    • Emma Storm
    • Francesca Calore
    Article
  • The MAVEN spacecraft observed brightening in the Lyman-α line correlated with solar wind activity, which can be attributed to auroral activity by solar wind protons interacting with the Martian neutral hydrogen corona. Proton aurorae are normally seen at Earth only.

    • J. Deighan
    • S. K. Jain
    • B. M. Jakosky
    Article
  • A model reconstructs the radiation dose from both protons and electrons on Europa’s surface. Using laboratory data on irradiated amino acids, it shows that organics can be preserved at detectable levels at depths of just a few centimetres at mid-to-high latitudes and in young (<10-Myr-old) terrains.

    • T. A. Nordheim
    • K. P. Hand
    • C. Paranicas
    Article
  • Reconstructing matter density from the velocities of local galaxies in a linear manner is standard practice. Averaging over the density fields of an ensemble of nonlinear simulations reveals a stronger galaxy ‘bias’ than in the linear regime, providing insights into the distribution of dark matter and the formation of galaxies.

    • Yehuda Hoffman
    • Edoardo Carlesi
    • Gustavo Yepes
    Article
  • Ground-based near-infrared spectra of Uranus detected hydrogen sulfide (H2S) above the main cloud deck (at a pressure of 1.2–3 bar), suggesting that the bulk sulfur/nitrogen ratio in Uranus’s atmosphere exceeds unity and that the clouds are dominated by H2S ice.

    • Patrick G. J. Irwin
    • Daniel Toledo
    • Bruno Bézard
    Article
  • How does Titan’s thick brownish haze chemically evolve as it is transported from the upper atmosphere observed by Cassini to the lower regions sampled by Huygens? Laboratory vacuum ultraviolet experiments may explain the observed changes in nitrogen chemistry.

    • Nathalie Carrasco
    • Sarah Tigrine
    • Murthy S. Gudipati
    Article
  • Titan's detached haze, a distinct layer on top of the main haze that provides a measure of the seasonal activity in the mesosphere, disappeared from 2012–2016, after equinox. Studying this transition will help us understand the dynamical and microphysical processes at work.

    • Robert A. West
    • Benoît Seignovert
    • Aida Ovanessian
    Article
  • An individual star at z = 1.49 is gravitationally lensed and highly magnified by a foreground galaxy cluster. Fluctuations in the star’s emission provide insight on the mass function of intracluster stars, compact objects and the presence of dark-matter subhaloes.

    • Patrick L. Kelly
    • Jose M. Diego
    • Benjamin J. Weiner
    Article
  • Two unusual transient events, discovered by Hubble behind a strong-lensing galaxy cluster, can be explained as separate eruptions of a luminous blue variable star or a recurrent nova, or as an unrelated pair of stellar microlensing events.

    • S. A. Rodney
    • I. Balestra
    • A. Zitrin
    Article
  • Laboratory analyses on six carbonaceous chondrites suggest the presence of two water sources with different deuterium (D) enrichment levels in the protoplanetary disk: a D-poor inner reservoir and a D-rich water component transferred inward from the outer disk.

    • Laurette Piani
    • Hisayoshi Yurimoto
    • Laurent Remusat
    Article
  • A model for the non-thermal emission of pulsars can fit their γ- and X-ray spectra using just four physical parameters. The model explains several spectral features, and can be used to predict the detectability of pulsars in X-rays given the γ-ray emission, and vice versa.

    • Diego F. Torres
    Article
  • Experiments are presented that indicate that methane can be produced abiotically on Mars through the photocatalytic reaction of CO2, in a process called methanogenesis. Methane can then be shocked (through impacts) to form RNA nucleobases and glycine.

    • Svatopluk Civiš
    • Antonín Knížek
    • Martin Ferus
    Article
  • By assessing the ionization fraction of the environment around Tycho’s (type Ia) supernova, the authors have constrained the properties of its progenitor enough to rule out a hot, luminous white dwarf. A double white dwarf binary merger is allowed.

    • T. E. Woods
    • P. Ghavamian
    • M. Gilfanov
    Article
  • A candidate dual supermassive black hole system with a projected separation of 0.35 pc is found in the gas-rich interacting spiral galaxy NGC 7674, evidenced by a ∼0.7 kpc Z-shaped radio jet and two, possibly inverted-spectrum, compact radio cores.

    • P. Kharb
    • D. V. Lal
    • D. Merritt
    Article
  • The authors present a spectrophotometric and hydrodynamical study of supernova OGLE-2014-SN-073, which had remarkably high inferred ejecta mass and energy, potentially higher than can be explained with canonical core-collapse neutrino-driven explosions.

    • G. Terreran
    • M. L. Pumo
    • K. Ulaczyk
    Article