Volume 3 Issue 9, September 2007

Volume 3 Issue 9

The final stages of planet formation take place within a disc of dust and gas surrounding a young star. Part of the disc spirals inwards onto the central star, dragging along the fledgling planets and setting their final orbits, but what drives this gas flow is still unclear. Eugene Chiang and Ruth Murray–Clay study the recently discovered 'transitional' discs, in which the innermost regions around a star are swept clean of dust. They propose that the dust-free condition enables a coupling between disc magnetic fields and rotating gas, owing to the ionization of the gas in the inner disc by X-rays emitted from the star. The ionized gas then activates a magnetic instability at the rim, which drives gas towards the central star while radiation pressure from the star pushes out any dust accompanying the infalling gas.

[Letter p604]

Editorial

  • Editorial |

    We regularly get queries about the minutiae of Nature Physics format, but what we really care about is that the papers are clear and accessibly written.

Commentary

  • Commentary |

    Brilliant scientists of all ages should be able to thrive at universities. Mandatory retirement is, therefore, a form of age discrimination, but its removal or postponement can come at a cost to younger faculty members, as observed in Italy.

    • Francesco Sylos Labini
    •  & Stefano Zapperi

Thesis

Books and Arts

Research Highlights

News and Views

  • News & Views |

    Vortex structures have revealed a lot about the nature of three-dimensional Bose–Einstein condensates. They play an even bigger part in two-dimensional cold atomic gases and drive a fundamentally different phase transition.

    • Keith Burnett
  • News & Views |

    Relativistic electrons in the outer Van Allen belt wreak havoc with satellites in geosynchronous orbit, but how they reach such high energies has been unclear. New data identify gyro-resonant wave–particle interactions as the culprit.

    • Richard Bertram Horne
  • News & Views |

    Biological cells respond actively to the physical properties of their surroundings as well as to external mechanical forces — a coupling that is captured in a model of a cell as a contractile dipole, and shown to drive cell re-orientation.

    • Florian Rehfeldt
    •  & Dennis E. Discher
  • News & Views |

    Quantum mechanics can simulate a classical system evolving in (and towards) thermal equilibrium. This finding adds a further ingredient to the story of what problems a computer — classical or quantum — could possibly master.

    • Giuseppe E. Santoro
    •  & Erio Tosatti
  • News & Views |

    The study of the critical state of matter has brought us concepts such as universality and power laws. Looking at mixtures of complex molecules could help us to understand the transition from non-critical to critical behaviour.

    • Luciano Reatto

Review

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