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Volume 4 Issue 9, September 2020

The ups and downs of cluster gas

The presence of cold gas in the centre of some galaxy clusters raises questions about its origin. Through a radiation-hydrodynamic simulation of active galactic nucleus feedback in such a cluster, Qiu et al. show that initially hot outflows can cool radiatively, forming extended filaments that resemble those observed.

See Qiu et al.

Image: Yu Qiu, KIAA-PKU/Georgia Tech Cover Design: Bethany Vukomanovic.


  • Quantitative estimates presented in this issue demonstrate that astronomers contribute more to climate change than the average global citizen. Concerted actions are needed to reduce the ecological impacts of our occupation.



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Comment & Opinion

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Books & Arts

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Research Highlights

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News & Views

  • The interstellar object ‘Oumuamua passed through the Solar System in 2017 and exhibited a puzzling combination of physical features. New work tells the story of this visitor.

    • Dimitri Veras
    News & Views
  • The upper atmospheres of all the giant planets are hotter than models predict. Analysis of Cassini Grand Finale observations of Saturn provide evidence that heat generated by the aurora is responsible.

    • Henrik Melin
    News & Views
  • A Galactic wind blowing from the Milky Way nucleus has swept up a few hundred clouds of atomic gas. New observations reveal dense molecular cores in two of these clouds, indicating a high loss rate of interstellar gas from the Galactic centre.

    • Mark R. Morris
    News & Views
  • The annual Fast Radio Burst conference was held as an entirely virtual event on 6–9 July inclusive, with talks spread over three time zones and an online communication channel for discussions.

    • Evan F. Keane
    Meeting Report
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  • Australian astronomers generate more greenhouse emissions than the average Australian citizen, thereby exacerbating the climate crisis. By quantifying contributions from different activities such as supercomputing and air travel, as presented here, astronomers can focus on reducing emissions by changing their practices in the most critical areas.

    • Adam R. H. Stevens
    • Sabine Bellstedt
    • Michael T. Murphy
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  • Tidal fragmentation of a planetary body that orbited too close to its star can explain all the peculiar characteristics of the interstellar visitor ‘Oumuamua, a formation model shows. Kilometre-sized comets, super-Earths and sub-Neptune exoplanets around subsolar stars or white dwarfs are the most probable parent bodies.

    • Yun Zhang
    • Douglas N. C. Lin
  • Interstellar comet Borisov has thus far looked very much like a Solar System comet in terms of its volatile content, but with new data from ALMA that show robust detections of CO and HCN, it is clear that Borisov is rich in CO, helping to pinpoint its origin.

    • M. A. Cordiner
    • S. N. Milam
    • D. C. Lis
  • Hubble Space Telescope data show that interstellar comet 2I/Borisov has an unusually high CO/H2O ratio—higher than any other comet that has been seen in the inner regions of our Solar System. This allows us to constrain the nature and location of the circumstellar region from which 2I/Borisov originated.

    • D. Bodewits
    • J. W. Noonan
    • Z.-X. Xing
  • It is difficult to reproduce the formation and composition of the moons of Uranus with a standard giant-impact model. Observations and modelling can be reconciled if the evolution of the water content in the disk, which is assumed to be vaporized and thus mostly accretes onto the planet before recondensation, is considered.

    • Shigeru Ida
    • Shoji Ueta
    • Yuya Ishizawa
  • Cataclysmic variables—a binary pairing of a white dwarf and a hydrogen-rich donor star—experience mass transfer and other complex interactions. This numerical simulation by Hillman et al. models in particular the feedback between the stellar pair, and succeeds in reproducing many of the observed characteristics of cataclysmic variables.

    • Yael Hillman
    • Michael M. Shara
    • Attay Kovetz
  • High-resolution radiation-hydrodynamic simulations of galaxy clusters show that extended cold gas filaments can form in the centre of clusters through the combination of radiative cooling and ram pressure from feedback driven by the central active galactic nucleus.

    • Yu Qiu
    • Tamara Bogdanović
    • Brian R. McNamara
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Mission Control

  • Optical communications will provide the next generation of interplanetary missions with high-bit-rate data transmission, requiring modifications on the ground and in space, explains Leslie Deutsch.

    • Leslie J. Deutsch
    Mission Control
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Amendments & Corrections

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