Volume 4 Issue 9, September 2020

Volume 4 Issue 9

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.

Editorial

  • Editorial |

    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.

Comment & Opinion

  • Comment |

    Analysing greenhouse gas emissions of an astronomical institute is a first step to reducing its environmental impact. Here, we break down the emissions of the Max Planck Institute for Astronomy in Heidelberg and propose measures for reductions.

    • Knud Jahnke
    • , Christian Fendt
    • , Morgan Fouesneau
    • , Iskren Georgiev
    • , Tom Herbst
    • , Melanie Kaasinen
    • , Diana Kossakowski
    • , Jan Rybizki
    • , Martin Schlecker
    • , Gregor Seidel
    • , Thomas Henning
    • , Laura Kreidberg
    •  & Hans-Walter Rix
  • Comment |

    Measuring the carbon emissions of the CFHT in 2019 reveals that the per employee emissions are 16.5 tCO2e, six times above the recommendation of the Paris Agreement, with ~63% due to the electricity consumption of the summit facility and ~25% to out-of-state air travel. Concerted efforts are underway to reduce this figure.

    • Nicolas Flagey
    • , Kahea Thronas
    • , Andreea Petric
    • , Kanoa Withington
    •  & M. Johannes Seidel
  • Comment |

    Computer use in astronomy continues to increase, and so also its impact on the environment. To minimize the effects, astronomers should avoid interpreted scripting languages such as Python, and favour the optimal use of energy-efficient workstations.

    • Simon Portegies Zwart
  • Comment |

    The annual meeting of the European Astronomical Society took place in Lyon, France, in 2019, but in 2020 it was held online only due the COVID-19 pandemic. The carbon footprint of the virtual meeting was roughly 3,000 times smaller than the face-to-face one, providing encouragement for more ecologically minded conferencing.

    • Leonard Burtscher
    • , Didier Barret
    • , Abhijeet P. Borkar
    • , Victoria Grinberg
    • , Knud Jahnke
    • , Sarah Kendrew
    • , Gina Maffey
    •  & Mark J. McCaughrean
  • Comment |

    Climate change is affecting and will increasingly affect astronomical observations, particularly in terms of dome seeing, surface layer turbulence, atmospheric water vapour content and the wind-driven halo effect in exoplanet direct imaging.

    • Faustine Cantalloube
    • , Julien Milli
    • , Christoph Böhm
    • , Susanne Crewell
    • , Julio Navarrete
    • , Kira Rehfeld
    • , Marc Sarazin
    •  & Anna Sommani

Books & Arts

Research Highlights

News & Views

  • 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
  • Meeting Report |

    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

Reviews

  • Perspective |

    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
    • , Pascal J. Elahi
    •  & Michael T. Murphy

Research

  • Letter |

    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
  • Letter |

    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
    • , N. Biver
    • , D. Bockelée-Morvan
    • , N. X. Roth
    • , E. A. Bergin
    • , E. Jehin
    • , A. J. Remijan
    • , S. B. Charnley
    • , M. J. Mumma
    • , J. Boissier
    • , J. Crovisier
    • , L. Paganini
    • , Y.-J. Kuan
    •  & D. C. Lis
  • Letter |

    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
    • , P. D. Feldman
    • , M. T. Bannister
    • , D. Farnocchia
    • , W. M. Harris
    • , J.-Y. Li
    • , K. E. Mandt
    • , J. Wm. Parker
    •  & Z.-X. Xing
  • Letter |

    The complete latitudinal coverage of Saturn’s thermospheric temperatures from Cassini Grand Finale data shows a more uniform spatial behaviour than model predictions, indicating an efficient redistribution of auroral energy from the poles towards the equator that could contribute to solving the giant planet’s energy crisis puzzle.

    • Z. Brown
    • , T. Koskinen
    • , I. Müller-Wodarg
    • , R. West
    • , A. Jouchoux
    •  & L. Esposito
  • Letter |

    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
    • , Takanori Sasaki
    •  & Yuya Ishizawa
  • Letter |

    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
    • , Dina Prialnik
    •  & Attay Kovetz
  • Letter |

    A recent supernova event, SN2016aps, must have involved an extremely energetic explosion and a very massive star, potentially indicating a pair-instability supernova or pulsational pair-instability supernova mechanism.

    • Matt Nicholl
    • , Peter K. Blanchard
    • , Edo Berger
    • , Ryan Chornock
    • , Raffaella Margutti
    • , Sebastian Gomez
    • , Ragnhild Lunnan
    • , Adam A. Miller
    • , Wen-fai Fong
    • , Giacomo Terreran
    • , Alejandro Vigna-Gómez
    • , Kornpob Bhirombhakdi
    • , Allyson Bieryla
    • , Pete Challis
    • , Russ R. Laher
    • , Frank J. Masci
    •  & Kerry Paterson
  • Letter |

    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
    • , Yuan Li
    • , Michael McDonald
    •  & Brian R. McNamara

Mission Control

  • 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

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