Astronomy and planetary science articles within Nature

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  • Review Article |

    The relativistic Big Bang theory is a good description of our expanding Universe. But — as discussed in this review article — a still better theory would describe a mechanism by which matter is more rapidly gathered into galaxies and groups of galaxies, better fitting the observations.

    • P. J. E. Peebles
    •  & Adi Nusser

  • News |

    Realistic computational models of supernovae might soon solve a long-standing mystery.

    • Eric Hand

  • News & Views |

    A fine marriage between galaxy data and theoretical simulations offers an explanation for two apparently conflicting sets of observations on the rate at which stars formed at early cosmic times.

    • Robert C. Kennicutt Jr

  • Letter |

    A pinwheel array of deep troughs has been one of the most perplexing features of the north polar layered deposits on Mars. Many ideas have been put forward about how it formed, but there is as yet no consensus. Here, penetrating radar has been used to rule out erosional cutting as a mechanism for the formation of the array. Instead, it is concluded that the troughs are largely depositional in origin, and have migrated to the poles and upwards in elevation over the past two million years or so.

    • Isaac B. Smith
    •  & John W. Holt

  • Letter |

    The Chasma Boreale is a large canyon — 500 km long, up to 100 km wide, and nearly 2 km deep — that cuts into the north polar layered deposits on Mars. Quite how it formed has been unclear. However, new penetrating radar imagery has now been used to show that depositional processes, rather than catastrophic events, were responsible.

    • J. W. Holt
    • , K. E. Fishbaugh
    •  & R. J. Phillips

  • Books & Arts |

    Brian Greene, author of best-selling books The Elegant Universe and The Fabric of the Cosmos, is a theoretical physicist at Columbia University, New York. As an orchestral work based on his 2008 children's book, Icarus at the Edge of Time, premieres next week, Greene discusses black holes and how music might portray the physics of warped space-time.

    • Jascha Hoffman

  • Letter |

    The unusual supernova SN 2005E is distinguished from any supernovae hitherto observed by several features, which are claimed to be explained by a helium detonation in a thin surface layer of an accreting white dwarf. The observed properties of SN 2005cz are now shown to resemble those of SN 2005E. It is argued that these properties are best explained by a core-collapse supernova at the low-mass end of the range of massive stars that explode.

    • K. S. Kawabata
    • , K. Maeda
    •  & K. Itagaki

  • Letter |

    Supernovae are thought to arise through one of two processes. Type Ib/c and type II supernovae are produced when the cores of massive, short-lived stars undergo gravitational core collapse and eject a few solar masses. Type Ia supernovae are thought to form by the thermonuclear detonation of a carbon-oxygen white dwarf. Here a faint type Ib supernova, SN 2005E, is reported that seems not to have had a core-collapse origin, but perhaps arose from a low-mass, old progenitor, probably a helium-accreting white dwarf in a binary.

    • H. B. Perets
    • , A. Gal-Yam
    •  & D. Poznanski

  • News & Views |

    Examples of stellar explosions have emerged that fall outside the traditional types of supernova. The nature of the stars that produce them and the mechanism by which they explode is far from clear.

    • David Branch

  • News & Views |

    The finding that some gas-giant exoplanets are much larger than theory predicts has been boggling astronomers' minds. Planetary heating caused by gravitational tidal interactions might be a piece of the puzzle.

    • Pin-Gao Gu

  • Letter |

    NGC 6791 is a well studied open cluster that is so close to us that it can be imaged down to very faint luminosities. Two different ages have been proposed for this cluster, one based on the white dwarf luminosity function and one derived from its main-sequence stars. The discrepancy in age is now resolved by the finding that, as theoretically anticipated, physical separation processes occur in the core of white dwarfs.

    • Enrique García-Berro
    • , Santiago Torres
    •  & Jordi Isern

  • Letter |

    Ultraluminous infrared galaxies are among the most luminous objects in the local Universe and are thought to be powered by intense star formation. In these objects, the rotational lines of molecular hydrogen (H2) observed at mid-infrared wavelengths are not affected by dust obscuration, but the source of excitation has been unknown. Here it is found that H2 emission originates outside the obscured regions; it is proposed that H2 emission traces shocks in the surrounding material that are excited by interactions with nearby galaxies.

    • Nadia L. Zakamska

  • News |

    Particle physicists in a race against time to overhaul US$1.5-billion cosmic-ray detector.

    • Edwin Cartlidge

  • Letter |

    Here, the atmosphere of the extrasolar planet GJ 436b is studied during its 'secondary eclipse'. The findings reveal the presence of some H2O and traces of CO2. The best-fit compositional models contain a high CO abundance and a substantial methane deficiency relative to thermochemical equilibrium models for the predicted hydrogen-dominated atmosphere. Disequilibrium processes such as vertical mixing and polymerization of methane may be required to explain this small methane-to-CO ratio.

    • Kevin B. Stevenson
    • , Joseph Harrington
    •  & Nate B. Lust

  • News |

    US President rallies support at NASA despite unpopular cuts to the Constellation rocket programme.

    • Mark Schrope

  • Letter |

    Three exoplanets around the star HR 8799 have recently been discovered by differential imaging with large telescopes. In such cases, bright scattered starlight means that large angular offsets of the star are required for high-contrast imaging of the planets. Imaging at small angles requires a technique for reducing starlight and associated noise while still transmitting light from the planet. Here such a technique is described: all three HR 8799 planets have been detected using a vector vortex coronagraph on a small-aperture system.

    • E. Serabyn
    • , D. Mawet
    •  & R. Burruss

  • Letter |

    ε Aurigae is a bright, eclipsing binary star system but the cause of each 18-month-long eclipse has been unknown for nearly 190 years, because the companion was, until recently, undetectable. The preferred explanation has been a tilted disk of opaque material and here the authors report interferometric images that do indeed show an opaque disk of very low mass, tilted as expected, crossing the disk of the F star.

    • Brian Kloppenborg
    • , Robert Stencel
    •  & Sean M. Carroll

  • News & Views |

    For more than a century, the binary star system ε Aurigae has been a riddle, wrapped in a mystery, inside an enigma. But no more — the system's previously inferred but unseen disk of dust has been detected.

    • Edward Guinan

  • News & Views |

    The asteroid belt is classically considered the domain of rocky bodies, being too close to the Sun for ice to survive. Or so we thought — not only is ice present, but at least one asteroid is covered in it.

    • Henry H. Hsieh

  • Letter |

    It has been suggested that Earth's current supply of water was delivered by asteroids. The presence of water on the surface of some asteroids has been inferred from the comet-like activity of several small asteroids, including two members of the Themis dynamical family, but hitherto has not been measured. Here, infrared spectra of the asteroid 24 Themis are reported; the results show that ice and organic compounds are not only present, but also prevalent, on its surface.

    • Humberto Campins
    • , Kelsey Hargrove
    •  & Julie Ziffer

  • Letter |

    The main observational signature of star-forming galaxies at the highest redshifts is the Lyman-α (Lyα) emission line. But Lyα photons scatter in the neutral interstellar medium of their host galaxies, and may therefore be greatly absorbed by interstellar dust. It is now shown that the average escaping fraction of Lyα photons from star-forming galaxies at redshift z = 2.2 is just 5 per cent. This implies that numerous conclusions based on Lyα-selected samples will require upwards revision by an order of magnitude.

    • Matthew Hayes
    • , Göran Östlin
    •  & Jens Melinder

  • Letter |

    Massive galaxies in the early Universe have been shown to be forming stars at high rates. Probing the properties of individual star-forming regions is beyond the resolution and sensitivity of existing telescopes. Here, however, observations are reported of the galaxy SMMJ2135–0102 at redshift z=2.3259, which has been gravitationally magnified by a factor of 32 by a galaxy cluster lens in the foreground. The physics underlying star formation here is similar to that in local galaxies, but the energetics are very different.

    • A. M. Swinbank
    • , I. Smail
    •  & J. D. Younger

  • Letter |

    The most distant quasars known, at redshifts z ≈ 6, generally have the same properties as lower-redshift quasars, implying that although the Universe was young at z ≈ 6, such quasars are still evolved objects. One z ≈ 6 quasar was shown to have no detectable emission from hot dust, but it was not clear whether it was an outlier. Now, a second quasar without hot-dust emission has been discovered in a sample of 21 z ≈ 6 quasars. Moreover, hot-dust abundance in these quasars builds up as the central black hole grows.

    • Linhua Jiang
    • , Xiaohui Fan
    •  & Fabian Walter

  • Letter |

    Of the more than 400 known exoplanets, about 70 transit their central star, most in small orbits (with periods of around 1 day, for instance). Here, observations are reported of the transit of CoRoT-9b, which orbits with a period of 95.274 days, on a low eccentricity, around a solar-like star. Its relatively large periastron distance yields a 'temperate' photospheric temperature estimated to be between 250 and 430 K, and its interior composition is inferred to be consistent with those of Jupiter and Saturn.

    • H. J. Deeg
    • , C. Moutou
    •  & G. Wuchterl

  • News & Views |

    The discovery of two quasars in the distant Universe that apparently have no hot dust in their environments provides evidence that these systems represent the first generation of their family.

    • Giulia Stratta

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