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Volume 2 Issue 4, April 2018

Perseus’s ancient edge still sharp

In the outer reaches of the Perseus galaxy cluster lies the five-billion-year-old relic ‘cold front’ produced by a cluster merger. Previously unseen structures found using deep Chandra X-ray Observatory images of this cold front provide powerful new insights into the astrophysics of galaxy clusters.

See Walker et al.

Image: Stephen A. Walker / NASA Goddard Space Flight Centre. Cover Design: Bethany Vukomanovic.


  • The proposed NASA budget promotes space exploration over science, and planetary science over astrophysics. This decision has the potential to cause strife between scientists, who have to work together to find a solution.



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Comment & Opinion

  • Hurricane Maria was 2 mph short of category 5 when it made landfall on Puerto Rico on 20 September 2017. The 305 m radio telescope at the Arecibo Observatory withstood the storm, suffering only minor structural damage. Staff have worked diligently to return the site to full operations and provide vital services to the surrounding Puerto Rican community.

    • Edgard G. Rivera-Valentín
    • Joan T. Schmelz
  • Awareness of light pollution is spreading, but with changing lighting technologies, emissions are shifting to wavelengths our current measuring devices cannot assess well. Community involvement is essential to evaluate changes in sky brightness.

    • Christopher C. M. Kyba
  • As with most data analysis methods, the Bayesian method must be handled with care. We show that its application to determine stellar evolution parameters within globular clusters can lead to paradoxical results if used without the necessary precautions. This is a cautionary tale on the use of statistical tools for big data analysis.

    • Francesca D’Antona
    • Vittoria Caloi
    • Marco Tailo
  • Radiative efficiency in radio-loud active galactic nuclei is governed by the accretion rate onto the central black hole rather than directly by the type of accreted matter; while it correlates with real differences in host galaxies and environments, it does not provide unambiguous information about particular objects.

    • Martin Hardcastle


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Books & Arts

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Research Highlights

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News & Views

  • Gravitational lensing is becoming increasingly important to the study of distant galaxies and dark matter. Two groups have recently detected transient events emanating from far-away lensed galaxies, apparently due to extreme magnification of individual stars.

    • Rosanne Di Stefano
    News & Views
  • The discovery of a prominent spectral absorption line in X-rays in an ultra-luminous X-ray source is perhaps indicative of the presence of very intense magnetic fields and hints to a magnetar as its power source.

    • Matthew G. Baring
    News & Views
  • Using evolving observing strategies and technologies we are catching supernovae closer and closer to the ‘b’ of the ‘bang’, thus unveiling new types of explosion mechanism that have not been studied in depth before.

    • J. J. Eldridge
    News & Views
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  • The only known planet whose densest part of the ionosphere is dominated by oxygen ions is Earth. The authors argue that this state is strictly related to the presence of photosynthesis. Ionospheric O+ can thus be used as a biomarker for exoplanets.

    • Michael Mendillo
    • Paul Withers
    • Paul A. Dalba
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  • Sloshing cold fronts in galaxy clusters—sharp jumps in density and temperature—retain a long-lived history of the motion of the cluster core. Chandra observations show that the cold front in Perseus is extremely sharp and is split into two edges.

    • Stephen A. Walker
    • John ZuHone
    • Jeremy Sanders


  • Laboratory experiments explore aerosol formation at conditions that can be found on planets with radii between Earth and Neptune that do not exist in the Solar System but are common elsewhere. Photochemically generated hazes are produced in most cases.

    • Sarah M. Hörst
    • Chao He
    • Véronique Vuitton
  • A fast-evolving luminous transient (FELT) has been detected with a rise time to peak luminosity of only 2.2 days. This implies that the light-curve of this FELT cannot be powered by the decay of radioactive elements, as with type Ia supernovae.

    • A. Rest
    • P. M. Garnavich
    • V. A. Villar
  • The power source of ultraluminous X-ray sources (ULXs) is still debated. A detection of an absorption line at 4.5 keV in the Chandra spectrum of a ULX supports the scenario of a strongly magnetized neutron star accreting at super-Eddington rates.

    • M. Brightman
    • F. A. Harrison
    • M. Bachetti
  • Laboratory analyses on six carbonaceous chondrites suggest the presence of two water sources with different deuterium (D) enrichment levels in the protoplanetary disk: a D-poor inner reservoir and a D-rich water component transferred inward from the outer disk.

    • Laurette Piani
    • Hisayoshi Yurimoto
    • Laurent Remusat
  • Two unusual transient events, discovered by Hubble behind a strong-lensing galaxy cluster, can be explained as separate eruptions of a luminous blue variable star or a recurrent nova, or as an unrelated pair of stellar microlensing events.

    • S. A. Rodney
    • I. Balestra
    • A. Zitrin
  • An individual star at z = 1.49 is gravitationally lensed and highly magnified by a foreground galaxy cluster. Fluctuations in the star’s emission provide insight on the mass function of intracluster stars, compact objects and the presence of dark-matter subhaloes.

    • Patrick L. Kelly
    • Jose M. Diego
    • Benjamin J. Weiner
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Amendments & Corrections

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Mission Control

  • The SPECULOOS project aims to detect terrestrial exoplanets well suited for detailed atmospheric characterization, explains Principal Investigator Michaël Gillon.

    • Michaël Gillon
    Mission Control
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