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51.
52.
John D. Monnier Stefan Kraus Michael J. Ireland Fabien Baron Amelia Bayo Jean-Philippe Berger Michelle Creech-Eakman Ruobing Dong Gaspard Duchêne Catherine Espaillat Chris Haniff Sebastian Hönig Andrea Isella Attila Juhasz Lucas Labadie Sylvestre Lacour Stephanie Leifer Antoine Merand Ernest Michael Stefano Minardi Christoph Mordasini David Mozurkewich Johan Olofsson Claudia Paladini Romain Petrov Jörg-Uwe Pott Stephen Ridgway Stephen Rinehart Keivan Stassun Jean Surdej Theo ten Brummelaar Neal Turner Peter Tuthill Kerry Vahala Gerard van Belle Gautam Vasisht Ed Wishnow John Young Zhaohuan Zhu 《Experimental Astronomy》2018,46(3):517-529
The Planet Formation Imager (PFI, www.planetformationimager.org) is a next-generation infrared interferometer array with the primary goal of imaging the active phases of planet formation in nearby star forming regions. PFI will be sensitive to warm dust emission using mid-infrared capabilities made possible by precise fringe tracking in the near-infrared. An L/M band combiner will be especially sensitive to thermal emission from young exoplanets (and their disks) with a high spectral resolution mode to probe the kinematics of CO and H2O gas. In this paper, we give an overview of the main science goals of PFI, define a baseline PFI architecture that can achieve those goals, point at remaining technical challenges, and suggest activities today that will help make the Planet Formation Imager facility a reality. 相似文献
53.
Christine S. Lane Maja Andrič Victoria L. Cullen Simon P.E. Blockley 《Quaternary Science Reviews》2011,30(9-10):1013-1018
The discovery of sites preserving tephra layers from multiple volcanic centres is key to constructing a single European tephrostratigraphic framework for the Late Quaternary. Until now, the tephrostratigraphy of Europe has been divided into two halves: sites in the North Atlantic and northern Europe regions link the Icelandic, Eifel, and the Massif Central volcanic histories; whilst sites in southern Europe record the sequence of tephra layers produced by circum-Mediterranean volcanic provinces. The missing link, able to tie together these two halves, is found in the tephrostratigraphic record of Lake Bled, Slovenia.Lake Bled, in the Julian Alps, Slovenia, holds a high resolution multi-proxy palaeoenvironmental archive for the Lateglacial of south-central Europe. Cryptotephra investigations have revealed three tephra layers: two closely spaced within Younger Dryas stadial sediments and one shortly after the start of the Bølling-Allerød interstadial warming. Two of the tephra layers (Bld_T120 and Bld_T240) are of Campanian origin and are correlated to deposits of the Pomici Principali (PP) and Neapolitan Yellow Tuff (NYT) eruptions, respectively. The third layer (Bld_T122) correlates to the Icelandic Vedde Ash (VA), extending the known fallout of this widespread marker layer farther to the southeast.The Lake Bled record also allows the stratigraphic relationship and relative ages of the VA and the PP eruption to be discerned for the first time. Whilst existing numerical age estimates for these two deposits are indistinguishable within errors, their close occurrence in the same lacustrine sediment sequence shows that the VA was erupted shortly prior to the PP eruption.The tephrostratigraphy of Lake Bled developed here helps us to tie together regional volcanic stratigraphies into a broader, continental-scale lattice of sites, with the potential to allow the transfer of dates between remote sequences and the construction of relative chronologies, beneficial in particular for environmental and archaeological research. 相似文献
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55.
Jin Ba Noel S. Keenlyside Wonsun Park Mojib Latif Ed Hawkins Hui Ding 《Climate Dynamics》2013,41(7-8):2133-2144
Atlantic Multidecadal Variability (AMV) is investigated in a millennial control simulation with the Kiel Climate Model (KCM), a coupled atmosphere–ocean–sea ice model. An oscillatory mode with approximately 60 years period and characteristics similar to observations is identified with the aid of three-dimensional temperature and salinity joint empirical orthogonal function analysis. The mode explains 30 % of variability on centennial and shorter timescales in the upper 2,000 m of the North Atlantic. It is associated with changes in the Atlantic Meridional Overturning Circulation (AMOC) of ±1–2 Sv and Atlantic Sea Surface Temperature (SST) of ±0.2 °C. AMV in KCM results from an out-of-phase interaction between horizontal and vertical ocean circulation, coupled through Irminger Sea convection. Wintertime convection in this region is mainly controlled by salinity anomalies transported by the Subpolar Gyre (SPG). Increased (decreased) dense water formation in this region leads to a stronger (weaker) AMOC after 15 years, and this in turn leads to a weaker (stronger) SPG after another 15 years. The key role of salinity variations in the subpolar North Atlantic for AMV is confirmed in a 1,000 year long simulation with salinity restored to model climatology: No low frequency variations in convection are simulated, and the 60 year mode of variability is absent. 相似文献
56.
57.
The 2dF Galaxy Redshift Survey: the dependence of galaxy clustering on luminosity and spectral type 总被引:1,自引:0,他引:1
Peder Norberg Carlton M. Baugh Ed Hawkins Steve Maddox Darren Madgwick Ofer Lahav Shaun Cole Carlos S. Frenk Ivan Baldry Joss Bland-Hawthorn Terry Bridges Russell Cannon Matthew Colless Chris Collins Warrick Couch Gavin Dalton Roberto De Propris Simon P. Driver George Efstathiou Richard S. Ellis Karl Glazebrook Carole Jackson Ian Lewis Stuart Lumsden John A. Peacock Bruce A. Peterson Will Sutherland Keith Taylor 《Monthly notices of the Royal Astronomical Society》2002,332(4):827-838
We investigate the dependence of galaxy clustering on luminosity and spectral type using the 2dF Galaxy Redshift Survey (2dFGRS). Spectral types are assigned using the principal-component analysis of Madgwick et al. We divide the sample into two broad spectral classes: galaxies with strong emission lines ('late types') and more quiescent galaxies ('early types'). We measure the clustering in real space, free from any distortion of the clustering pattern owing to peculiar velocities, for a series of volume-limited samples. The projected correlation functions of both spectral types are well described by a power law for transverse separations in the range 2<( σ / h -1 Mpc)<15 , with a marginally steeper slope for early types than late types. Both early and late types have approximately the same dependence of clustering strength on luminosity, with the clustering amplitude increasing by a factor of ∼2.5 between L * and 4 L *. At all luminosities, however, the correlation function amplitude for the early types is ∼50 per cent higher than that of the late types. These results support the view that luminosity, and not type, is the dominant factor in determining how the clustering strength of the whole galaxy population varies with luminosity. 相似文献
58.
When the shock wave from a supernova expands, it sweeps up not only interstellar matter but also magnetic field. The field is greatly amplified by compression and will provide the dominant pressure during the cool radiative phase of an expanding supernova shell. We examine a hydromagnetic instability in this system (a form of the Parker instability) and find that it will concentrate gas at intervals of the order of parsecs. The length and time scales make the instability promising as an explanation of the stellar clustering that is seen in Canis Major R1. 相似文献
59.
Katherine Boggs David Eaton Thomas James Roy Hyndman Malaika Ulmi Pascal Audet Ed Johnston Michael Sideris Ron Clowes Julie Elliott Jeff Freymueller Paul Kushner Kristin Morell Derek Schutt Rick Aster Frank Vernon Michael Hedlin Catherine de Groot-Hedlin Eric Donovan Roland Stull 《《地质学报》英文版》2018,92(Z1):12-13
60.
Patricia C. Fanning Simon J. Holdaway Ed J. Rhodes Tessa G. Bryant 《Geoarchaeology》2009,24(2):121-146
The conventional approach to assessing the archaeological record in most parts of the world involves a combination of excavation of stratified deposits and extensive survey of surface deposits. Although widely applied in Australia, in both research‐based and management archaeology, the method does not conform well to the nature of the surface archaeological record here. Over much of semi‐arid and arid Australia, archaeological “sites” are, in fact, accretion phenomena that are not easily interpreted as the outcome of short‐term behavioral events. Using results from twelve years of geoarchaeological research in western New South Wales, we demonstrate that there is considerable variability in landsurface age, and hence the “availability” of archaeological surfaces, over relatively short distances. Therefore, it cannot be assumed that stone artifact deposits, for example, that appear to be similar in character are of similar age. Data are also presented that demonstrate that the presence of artifacts on the surface, their apparent absence in sediments buried beneath the surface, and the apparent recent ubiquity of the archaeological record are all a function of geomorphic processes that, at the same time, expose some artifact deposits at the surface and erode and bury others amid large volumes of sediment. Interpreting the surface artifact record within a spatial and temporal geomorphic framework is crucial to understanding the past human behavior that the artifact deposits represent. © 2009 Wiley Periodicals, Inc. 相似文献