Reviews & Analysis

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  • The precise location of megamaser emission regions in galactic accretion disks has been challenging to pinpoint. Now with interferometric observations leveraging baselines larger than the Earth’s diameter, the missing information is getting closer and closer.

    • C. M. Violette Impellizzeri
    News & Views
  • Observations have mapped the distribution of gas velocities in a circumstellar disk wind for the first time. The high spatial resolution required for these observations is achieved by measuring the maser emission of water molecules. These findings validate theoretical predictions from the 1980s and can be replicated by modern numerical models.

    Research Briefing
  • A number of recent laboratory studies—summarized in this Review—have improved our understanding of the origin of presolar grains, with at least a quarter of presolar grains now being understood to originate in supernovae and their progenitors.

    • Peter Hoppe
    • Jan Leitner
    • Anthony P. Jones
    Review Article
  • This review summarizes our understanding of early-type dwarfs, which are the end-points of the evolution of low-mass galaxies. Their primeval stellar populations provide a unique laboratory for studying the physical conditions on small scales at epochs beyond z = 2.

    • Vasily Belokurov
    • N. Wyn Evans
    Review Article
  • A unified theory of particle transport by wind can explain the observations of aeolian features, like dunes, across the Solar System rocky bodies with atmospheres.

    • Hezi Yizhaq
    • Simone Silvestro
    News & Views
  • The internal and external pressure of interstellar medium clouds were measured by modelling of Atacama Large Millimeter Array and Very Large Telescope data. Pressure gradients indicated that both cloud collapse and expansion are possible in jet-driven outflows from black holes, potentially altering the star formation rate of their galaxies.

    Research Briefing
  • Conflicting results in measurements of the global spectrum of the hydrogen 21-cm line may indicate that there are large systematic errors. A different experimental approach to reach the redshifted signal from cosmic dawn assesses possible systematic errors together with the signal.

    • Xuelei Chen
    News & Views
  • Certain types of strongly star-forming galaxies have long been thought to lie outside the usual trends in metal abundances followed by other galaxies. A study now reveals the significant effect of dust on observations, bringing these galaxies back into line with models.

    • François Hammer
    News & Views
  • Ultraviolet-detected Fermi bubble clouds have metallicities that are consistent with the clouds having two origins: the Milky Way disk and halo. This result adds complexity to the previously accepted picture that these clouds could only be launched from the disk of the Milky Way into the bubbles.

    Research Briefing
  • Although the Earth is depleted in volatile components relative to its potential chondritic precursors, the isotopic compositions of these elements are similar in Earth and chondrites. A theory to explain these observations suggests that rocky material that formed at various temperatures, locations and times in the protoplanetary disk collected to make Earth.

    Research Briefing
  • Recent advances in plasma turbulence theory have led to a new way of explaining the heating of the solar corona and many of the observed features of the solar wind.

    • Christopher H. K. Chen
    News & Views
  • As the population of Earth’s orbital environment and human exploration of space intensifies, it is critical to have a strong ethical framework in place so that mistakes of the past are learned from and not repeated.

    • Emily C. Martin
    • Lucianne Walkowicz
    • Monica Vidaurri
    Meeting Report
  • The Rosetta mission to comet 67P/Churyumov–Gerasimenko found unexpectedly high concentrations of molecular oxygen in its atmosphere. New results show that these concentrations are enhanced by a cycle of trapping and releasing of molecular oxygen just below the comet’s surface.

    • Dennis Bodewits
    • Mohammad Saki
    News & Views