Volume 2 Issue 5, May 2018

Volume 2 Issue 5

No pristine comets

The bilobate form of many cometary nuclei is usually associated with low-speed merging of two bodies occurring in the early phase of our Solar System. Simulations show another pathway to bilobate formation: aggregation of material after a catastrophic impact. This process can occur at any time, so bilobate comets don’t necessarily have to be primordial, as previously thought.

See Schwartz et al.

Image: Stephen R. Schwartz, University of Arizona/Observatoire de la Côte d'Azur. Cover Design: Bethany Vukomanovic

Editorial

Comment & Opinion

  • Comment |

    China has approved or planned a string of several space exploration missions to be launched over the next decade. A new generation of planetary scientists in China is playing an important role in determining the scientific goals of future missions.

    • Yong Wei
    • , Zhonghua Yao
    •  & Weixing Wan
  • Comment |

    Investments in national astronomical facilities and human resources through the National Astronomical Research Institute of Thailand have led to the rapid growth of astronomy in Thailand. Ongoing activities in key research areas, education and outreach will lead to further sustainable development.

    • Boonrucksar Soonthornthum

Books & Arts

Research Highlights

News & Views

  • News & Views |

    Observations of two sequences of blue stragglers in a young, sparse star cluster in the Large Magellanic Cloud re-opens the debate about the dominant formation mechanism of these anomalous stars.

    • Alison Sills
  • News & Views |

    Hydrogen sulfide gas is detected above Uranus’s main cloud deck, confirming the prevalence of H2S ice particles as the main cloud component and a strongly unbalanced nitrogen/sulfur ratio in the planet's deep atmosphere.

    • Imke de Pater

Reviews

  • Perspective |

    CubeSats, a standardized subgroup of small satellites, are a cheap and flexible solution to perform astronomical observations from space that is just starting to be exploited. This Perspective presents an overview of their advantages and of the current and planned projects.

    • Evgenya L. Shkolnik

Research

  • Letter |

    This paper puts into question the standard scenario of a primordial formation for bilobate comets. The authors show that bilobate comets can retain their properties even if they form through collisions of larger bodies, which can happen at any time.

    • Stephen R. Schwartz
    • , Patrick Michel
    • , Martin Jutzi
    • , Simone Marchi
    • , Yun Zhang
    •  & Derek C. Richardson
  • Letter |

    The brightness variations of the interstellar object 1I/’Oumuamua observed during six nights are incompatible with a unique rotation rate, indicating that the body is tumbling. Colour measurements suggest a heterogeneous surface, with a large red region.

    • Wesley C. Fraser
    • , Petr Pravec
    • , Alan Fitzsimmons
    • , Pedro Lacerda
    • , Michele T. Bannister
    • , Colin Snodgrass
    •  & Igor Smolić
  • Letter |

    New hydrodynamical models are used to fit the Fermi-LAT data of the Galactic centre and show that the excess γ-ray emission of the region is better fitted by a non-spherical shape, indicating that it is not caused by dark-matter-related phenomena.

    • Oscar Macias
    • , Chris Gordon
    • , Roland M. Crocker
    • , Brendan Coleman
    • , Dylan Paterson
    • , Shunsaku Horiuchi
    •  & Martin Pohl
  • Letter |

    The abundance of metals in Mercury’s interior is unique among the rocky planets of the Solar System. The characterization of the ‘super-Mercury’ exoplanet presented in this paper will improve our understanding of how Mercury-like planets can form and evolve.

    • A. Santerne
    • , B. Brugger
    • , D. J. Armstrong
    • , V. Adibekyan
    • , J. Lillo-Box
    • , H. Gosselin
    • , A. Aguichine
    • , J.-M. Almenara
    • , D. Barrado
    • , S. C. C. Barros
    • , D. Bayliss
    • , I. Boisse
    • , A. S. Bonomo
    • , F. Bouchy
    • , D. J. A. Brown
    • , M. Deleuil
    • , E. Delgado Mena
    • , O. Demangeon
    • , R. F. Díaz
    • , A. Doyle
    • , X. Dumusque
    • , F. Faedi
    • , J. P. Faria
    • , P. Figueira
    • , E. Foxell
    • , H. Giles
    • , G. Hébrard
    • , S. Hojjatpanah
    • , M. Hobson
    • , J. Jackman
    • , G. King
    • , J. Kirk
    • , K. W. F. Lam
    • , R. Ligi
    • , C. Lovis
    • , T. Louden
    • , J. McCormac
    • , O. Mousis
    • , J. J. Neal
    • , H. P. Osborn
    • , F. Pepe
    • , D. Pollacco
    • , N. C. Santos
    • , S. G. Sousa
    • , S. Udry
    •  & A. Vigan
  • Letter |

    Cosmic filaments evolve nonlinearly from density fluctuations produced in the primordial Universe. Detection of cosmic microwave background lensing by filaments allows the measurement of how filaments trace the matter distribution on large scales.

    • Siyu He
    • , Shadab Alam
    • , Simone Ferraro
    • , Yen-Chi Chen
    •  & Shirley Ho
  • Letter |

    1I/‘Oumuamua observations from the Gemini North telescope, spanning approximately 8 hours on 27–28 October 2017, characterize the magnitude variations of the object and detect its tumbling nature, triggered by an old collision when it was still in its home system.

    • Michał Drahus
    • , Piotr Guzik
    • , Wacław Waniak
    • , Barbara Handzlik
    • , Sebastian Kurowski
    •  & Siyi Xu
  • Article |

    Pyrene, a polycyclic aromatic hydrocarbon composed of four fused benzene rings, is putatively a key molecule in the formation of 2D carbonaceous structures. Using experimental and computational techniques, Zhao et al. show that pyrene can form in circumstellar conditions.

    • Long Zhao
    • , Ralf I. Kaiser
    • , Bo Xu
    • , Utuq Ablikim
    • , Musahid Ahmed
    • , Dharati Joshi
    • , Gregory Veber
    • , Felix R. Fischer
    •  & Alexander M. Mebel
  • 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
    • , Ryan Garland
    • , Nicholas A. Teanby
    • , Leigh N. Fletcher
    • , Glenn A. Orton
    •  & Bruno Bézard

Amendments & Corrections

Mission Control

  • Mission Control |

    Observational astronomy in Iran has witnessed a rise over the past two decades that has led to investment in its own astronomical identity, the Iranian National Observatory, and a flagship 3.4-m optical telescope.

    • Habib G. Khosroshahi