Astronomy and astrophysics articles within Nature

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  • News & Views |

    In some galaxies, matter falling onto a supermassive black hole is ejected in narrow jets moving at close to the speed of light. New observations provide insight into the workings of these cosmic accelerators.

    • Andy Young

  • Letter |

    Stars form from cold molecular interstellar gas, which is relatively rare in the local Universe, such that galaxies like the Milky Way form only a few new stars per year. However, typical massive galaxies in the distant Universe formed stars much more rapidly, suggesting that young galaxies were more rich in molecular gas. The results of a survey of molecular gas in samples of typical massive star-forming galaxies when the Universe was 40% and 24% of its current age now reveal that distant star-forming galaxies were indeed gas rich.

    • L. J. Tacconi
    • , R. Genzel
    •  & B. Weiner

  • News & Views |

    The cool molecular gas from which stars form has been detected in relatively ordinary faraway galaxies. The results point to a continuous fuelling of gas into the star-forming guts of assembling galaxies.

    • Andrew Blain

  • Letter |

    Infrared spectroscopy can probe the conditions and compositions of exoplanet atmospheres. Previous results relied on space-based telescopes that do not provide spectroscopic capability in the 2.4–5.2 μm spectral region. Here, ground-based observations of the dayside emission spectrum for HD 189733b are reported between 2.0–2.4 μm and 3.1–4.1 μm; an unexpected feature at around 3.25 μm is found that is difficult to explain with models that assume local thermodynamic equilibrium conditions, and is assigned to methane.

    • Mark R. Swain
    • , Pieter Deroo
    •  & Thomas Henning

  • Letter |

    Long duration γ-ray bursts mark the explosive death of some massive stars and are a rare sub-class of type Ibc supernovae. To date, central-engine-driven supernovae have been discovered exclusively through their γ-ray emission, yet it is expected that a larger population goes undetected. The discovery of luminous radio emission from the seemingly ordinary type Ibc supernova SN 2009bb, which requires a substantial relativistic outflow powered by a central engine, is now reported.

    • A. M. Soderberg
    • , S. Chakraborti
    •  & M. A. P. Torres

  • Letter |

    Type Ic supernovae have drawn attention since 1998 owing to their sparse association with long duration γ-ray bursts (GRBs). Although the GRB central engine generates ultra-relativistic jets, no relativistic outflows have yet been found in type Ib/c supernovae explosions. Here, radio observations reveal a mildly relativistic expansion in a nearby type Ic supernova, SN 2007gr.

    • Z. Paragi
    • , G. B. Taylor
    •  & B. Paczyński

  • Letter |

    The properties of 'dwarf' galaxies have long challenged the cold dark matter (CDM) model of galaxy formation, as the properties of most observed dwarf galaxies contrast with models based on the dominance of CDM. Here, hydrodynamical simulations (assuming the presence of CDM) are reported in which the analogues of dwarf galaxies — bulgeless and with shallow central dark-matter profiles — arise naturally.

    • F. Governato
    • , C. Brook
    •  & P. Madau

  • Letter |

    The close binary Algol system contains a radio-bright KIV sub-giant star in a very close and rapid orbit with a main sequence B8 star. Evidence points to the existence of an extended, complex coronal magnetosphere originating at the cooler K subgiant, but the detailed morphology of the subgiant's corona and its possible interaction with its companion are unknown. Multi-epoch radio imaging of the Algol system now reveals a large coronal loop suggestive of a persistent asymmetric magnetic field structure aligned between the two stars.

    • W. M. Peterson
    • , R. L. Mutel
    •  & W. M. Goss

  • News & Views |

    Windy weather is forecast where stars are forming. Numerical simulations show that these winds can reshape dwarf galaxies, reconciling their properties with the prevailing theory of galaxy formation.

    • Marla Geha

  • Letter |

    The amplitude of the magnetic field near the Galactic Centre has been uncertain by two orders of magnitude for several decades. A compilation of previous data now reveals a downward break in the region's non-thermal radio spectrum; this requires that the Galactic Centre field be at least ∼50 microgauss on 400 parsec scales, with evidence supporting a field of 100 microgauss. This would imply that over 10% of the Galaxy's magnetic energy is contained in only around 0.05% (or less) of its volume.

    • Roland M. Crocker
    • , David I. Jones
    •  & Raymond J. Protheroe

  • Letter |

    Existing models of type Ia supernovae generally explain their observed properties, with the exception of the sub-luminous 1991bg-like supernovae. It has long been suspected that the merger of two white dwarfs could give rise to a type Ia event, but simulations so far have failed to produce an explosion. Here, a simulation of the merger of two equal-mass white dwarfs is presented that leads to a sub-luminous explosion; it requires a single common-envelope phase and component masses of about 0.9 solar masses.

    • Rüdiger Pakmor
    • , Markus Kromer
    •  & Wolfgang Hillebrandt

  • News & Views |

    The progenitors of type Ia supernovae, the standard candles that lit the way to dark energy, have been elusive. A largely dismissed scenario has now produced one, but the results aren't what anyone expected.

    • D. Andrew Howell

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