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Volume 2 Issue 5, May 2018

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

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Comment & Opinion

  • 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
    Comment
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Books & Arts

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Research Highlights

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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
    News & Views
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Reviews

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Research

  • 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
    • 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
    • Igor Smolić
    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
    • A. Vigan
    Letter
  • 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
    • Bruno Bézard
    Article
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Amendments & Corrections

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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
    Mission Control
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