Volume 2 Issue 7, July 2018

Volume 2 Issue 7

The shadow of a black hole

Properties of the shadow cast by a black hole due to extreme lensing should help discriminate between models of gravity. But simulations show that the silhouettes of a rotating Kerr black hole (general relativity) and a non-rotating black hole (with a dilaton field) are sufficiently similar that the Event Horizon Telescope cannot presently tell the difference.

See See Mizuno et al.

Image: Ziri Younsi, Yosuke Mizuno, Christian Fromm, Luciano Rezzolla, Goethe University Frankfurt. Cover Design: Bethany Vukomanovic.

Editorial

Correspondence

Comment & Opinion

  • Comment |

    The Development in Africa with Radio Astronomy (DARA) project, a joint venture between the UK, South Africa and African partner nations, aims to provide development, education, training and careers advice to Africans through radio astronomy and related technical disciplines.

    • Melvin G. Hoare
  • Comment |

    The development of astronomy and space science in Africa has grown significantly over the past few years. These advancements make the United Nations Sustainable Development Goals more achievable, and open up the possibility of new beneficial collaborations.

    • Mirjana Pović
    • , Michael Backes
    • , Paul Baki
    • , David Baratoux
    • , Solomon Belay Tessema
    • , Zouhair Benkhaldoun
    • , Michael Bode
    • , Nana A. Browne Klutse
    • , Phil Charles
    • , Kevin Govender
    • , Ernst van Groningen
    • , Edward Jurua
    • , Alemiye Mamo
    • , Sivuyile Manxoyi
    • , Vanessa McBride
    • , Jamal Mimouni
    • , Takalani Nemaungani
    • , Pheneas Nkundabakura
    • , Bonaventure Okere
    • , Somaya Saad
    • , Prospery C. Simpemba
    • , Tefera Walwa
    •  & Abdissa Yilma
  • Comment |

    Since 2013, the International Astronomical Union’s Office of Astronomy for Development has been funding and nurturing astronomy-for-development projects across the globe. In Africa, these projects aim to use astronomy to stimulate educational, technological and socioeconomic development.

    • Vanessa McBride
    • , Ramasamy Venugopal
    • , Munira Hoosain
    • , Tawanda Chingozha
    •  & Kevin Govender

Books & Arts

Research Highlights

News & Views

  • News & Views |

    The Juno spacecraft has detected unprecedented numbers of ‘whistlers’ and ‘sferics’ in its orbits around Jupiter, both indications of high lightning flash rates in the atmosphere of the gas giant planet.

    • Jacob Bortnik
  • Meeting Report |

    ‘Why is there a black hole where women should be?’ asked Member of Parliament Chi Onwurah during her plenary talk on women in science at EWASS 2018. Gender equity was among a variety of topics discussed in a day-long Special Session.

    • Helen E. Jermak
    • , Sara Lucatello
    •  & Paul Woods
  • Meeting Report |

    A diverse group of science communicators from around the world came together in Fukuoka, Japan to discuss outreach strategies in a post-factual society, methods to improve inclusion, best practices for communicating within international collaborations and resources to benefit localized organizations.

    • Amanda E. Bauer
    • , Samir Dhurde
    •  & Olayinka Fagbemiro
  • News & Views |

    New analyses show that most asteroids, nowadays residing in the main belt between Mars and Jupiter, could have originated from collisional events that have broken apart a few large parent bodies.

    • Bojan Novaković

Reviews

  • Perspective |

    Should science be taught differently? By emphasizing the process, not the acquisition of factual knowledge, students will learn how to solve problems and see science as relevant to their careers outside of research.

    • Sun Kwok
  • Review Article |

    General relativity underwent a conceptual transformation after World War II that can be used to understand the hitherto vaguely defined ‘renaissance of general relativity’, which led to the prediction and eventual discovery of gravitational waves.

    • Alexander Blum
    • , Roberto Lalli
    •  & Jürgen Renn

Research

  • Letter |

    The Waves instrument on board the Juno spacecraft has detected ~1,600 lightning strokes in roughly 1 year of close approaches to Jupiter, indicated by low-dispersion rapid whistlers much shorter than those detected by Voyager 1 in Io’s plasma torus.

    • Ivana Kolmašová
    • , Masafumi Imai
    • , Ondřej Santolík
    • , William S. Kurth
    • , George B. Hospodarsky
    • , Donald A. Gurnett
    • , John E. P. Connerney
    •  & Scott J. Bolton
  • Letter |

    All inner main-belt asteroids, and not just those belonging to a specific family as previously thought, originate from the splintering of a few large asteroids. The history of such precursors determines the compositional variety we observe in asteroids and meteorites.

    • Stanley F. Dermott
    • , Apostolos A. Christou
    • , Dan Li
    • , Thomas. J. J. Kehoe
    •  & J. Malcolm Robinson
  • Letter |

    Images of 67P's nucleus from the Rosetta spacecraft, together with numerical simulations, show that the jet-like features of cometary comae can be produced by diffuse activity focused by the nucleus topography as well as non-uniform insolation over the surface.

    • X. Shi
    • , X. Hu
    • , S. Mottola
    • , H. Sierks
    • , H. U. Keller
    • , M. Rose
    • , C. Güttler
    • , M. Fulle
    • , S. Fornasier
    • , J. Agarwal
    • , M. Pajola
    • , C. Tubiana
    • , D. Bodewits
    • , C. Barbieri
    • , P. L. Lamy
    • , R. Rodrigo
    • , D. Koschny
    • , M. A. Barucci
    • , J.-L. Bertaux
    • , I. Bertini
    • , S. Boudreault
    • , G. Cremonese
    • , V. Da Deppo
    • , B. Davidsson
    • , S. Debei
    • , M. De Cecco
    • , J. Deller
    • , O. Groussin
    • , P. J. Gutiérrez
    • , S. F. Hviid
    • , W.-H. Ip
    • , L. Jorda
    • , J. Knollenberg
    • , G. Kovacs
    • , J.-R. Kramm
    • , E. Kührt
    • , M. Küppers
    • , L. M. Lara
    • , M. Lazzarin
    • , J. J. Lopez-Moreno
    • , F. Marzari
    • , G. Naletto
    • , N. Oklay
    • , I. Toth
    •  & J.-B. Vincent
  • Letter |

    Analysis of a six-year time series of SDO/HMI images of the solar photosphere reveals the existence of global-scale equatorial Rossby waves in the Sun, which contain a large fraction of the radial vorticity at these scales.

    • Björn Löptien
    • , Laurent Gizon
    • , Aaron C. Birch
    • , Jesper Schou
    • , Bastian Proxauf
    • , Thomas L. Duvall Jr
    • , Richard S. Bogart
    •  & Ulrich R. Christensen
  • Letter |

    Supernova SN 2015bs is a hydrogen-rich type II supernova that appears to have been generated by a high-mass (>18 M) and low-metallicity (<0.1 Z) red supergiant progenitor.

    • J. P. Anderson
    • , L. Dessart
    • , C. P. Gutiérrez
    • , T. Krühler
    • , L. Galbany
    • , A. Jerkstrand
    • , S. J. Smartt
    • , C. Contreras
    • , N. Morrell
    • , M. M. Phillips
    • , M. D. Stritzinger
    • , E. Y. Hsiao
    • , S. González-Gaitán
    • , C. Agliozzo
    • , S. Castellón
    • , K. C. Chambers
    • , T. -W. Chen
    • , H. Flewelling
    • , C. Gonzalez
    • , G. Hosseinzadeh
    • , M. Huber
    • , M. Fraser
    • , C. Inserra
    • , E. Kankare
    • , S. Mattila
    • , E. Magnier
    • , K. Maguire
    • , T. B. Lowe
    • , J. Sollerman
    • , M. Sullivan
    • , D. R. Young
    •  & S. Valenti
  • Letter |

    Until recently, stellar evolution models had not been able to explain the presence of bright planetary nebulae in old stellar populations. Using the revised evolutionary tracks of Miller Bertolami (2016), it is now evident that lower-mass and longer-lived planetary nebulae can be bright.

    • K. Gesicki
    • , A. A. Zijlstra
    •  & M. M. Miller Bertolami
  • Letter |

    The authors predict the ability of the Event Horizon Telescope (in its 2017 campaign) to distinguish between different theories of gravity based on images of Sagittarius A*; they suggest that it will not be possible.

    • Yosuke Mizuno
    • , Ziri Younsi
    • , Christian M. Fromm
    • , Oliver Porth
    • , Mariafelicia De Laurentis
    • , Hector Olivares
    • , Heino Falcke
    • , Michael Kramer
    •  & Luciano Rezzolla

    Insight:

Amendments & Corrections

Mission Control

  • Mission Control |

    The HESS array in Namibia waits for a split-second flash of blue light — Cherenkov radiation — that signals an atmospheric shower of charged particles caused by cosmic rays, explains Director Mathieu de Naurois.

    • Mathieu de Naurois