Structural properties of discs and bulges of early-type galaxies     

Roelof S. de Jong  Luc Simard  Roger L. Davies  R. P. Saglia  David Burstein  Matthew Colless  Robert McMahan  Gary Wegner 《Monthly notices of the Royal Astronomical Society》2004,355(4):1155-1170

  相似文献   

Gemini/GMOS spectra of globular clusters in the Leo group elliptical NGC 3379     

Michael Pierce  Michael A. Beasley  Duncan A. Forbes  Terry Bridges  Karl Gebhardt  Favio Raul Faifer  Juan Carlos Forte  Stephen E. Zepf  Ray Sharples  David A. Hanes  Robert Proctor 《Monthly notices of the Royal Astronomical Society》2006,366(4):1253-1264

  相似文献   

The Hubble Deep Field-North SCUBA Super-map – IV. Characterizing submillimetre galaxies using deep Spitzer imaging     

Alexandra Pope  Douglas Scott  Mark Dickinson  Ranga-Ram Chary  Glenn Morrison  Colin Borys  Anna Sajina  David M. Alexander  Emanuele Daddi †  David Frayer  Emily MacDonald  Daniel Stern 《Monthly notices of the Royal Astronomical Society》2006,370(3):1185-1207

  相似文献   

Late glacial and Holocene environmental change in the Lake Baikal region documented by oxygen isotopes from diatom silica   总被引：4，自引：0，他引：4  

David W. Morley  Melanie J. Leng  Anson W. Mackay  Hilary J. Sloane 《Global and Planetary Change》2005,46(1-4):221

We investigate late glacial and Holocene climate change recorded in Lake Baikal using the oxygen isotope composition of diatom silica (δ¹⁸O_DIAT). Evaporation from the lake is minor, and the temperature fractionations of δ¹⁸O are unable to explain variations in the δ¹⁸O_DIAT record alone. Isotopically, low meltwater input from glaciers may have some influence on δ¹⁸O_DIAT, but the assumed periods of climatic warming and wastage do not coincide with large shifts in δ¹⁸O_DIAT. There is a gradual oxygen isotope lowering from 27.0‰ to 20.6‰ over the late glacial, while, during the Holocene, δ¹⁸O_DIAT values return to relatively high values. Previous studies of the modern oxygen and hydrogen isotope composition of Lake Baikal's inputs reveal that fluvial input to the lake's North Basin are isotopically lower than fluvial input from South Basin rivers. This north–south gradient of river δ¹⁸O and δD is mainly due to the greater input from isotopically low winter precipitation in the north and isotopically higher summer precipitation in the south. As a result, the δ¹⁸O_DIAT record from Lake Baikal can at least in part be explained by varying input from these sources related to seasonal changes in precipitation. Changes in atmospheric conditions may have a role in altering seasonality and the distribution of precipitation over Lake Baikal's catchment. A feedback mechanism is well known linking higher Eurasian spring snow cover extent (ESSC) to the development of anticyclonic conditions and low precipitation the following summer in the areas south of Lake Baikal. A simultaneous increase in the importance of depleted water (snowmelt) input from the north and decreased enriched summer precipitation in the south is needed to explain depletions in δ¹⁸O of lake water and subsequently δ¹⁸O_DIAT during colder periods. The opposite of this situation is required to enrich lake water during warmer periods. The analysis of δ¹⁸O from diatom silica is a useful proxy for environmental change, especially in lakes, like Lake Baikal, where carbonates are absent or diluted. However, analysis must be based on near pure diatom samples as even trace amounts of silt can have a dominating effect on δ¹⁸O_DIAT values.  相似文献   

Accurate orbital parameters for the bright southern spectroscopic binary ζ Trianguli Australis – an interesting case of a near-circular orbit     

Jovan Skuljan  David J. Ramm  John B. Hearnshaw 《Monthly notices of the Royal Astronomical Society》2004,352(3):975-983

  相似文献   

Formation of Kuiper-belt binaries through multiple chaotic scattering encounters with low-mass intruders     

Sergey A. Astakhov  Ernestine A. Lee  David Farrelly 《Monthly notices of the Royal Astronomical Society》2005,360(2):401-415

  相似文献   

Streaming motions of galaxy clusters within 12 000 km s⁻¹– III. A standardized catalogue of Fundamental Plane data     

Michael J. Hudson  John R. Lucey  Russell J. Smith  David J. Schlegel  Roger L. Davies 《Monthly notices of the Royal Astronomical Society》2001,327(1):265-295

  相似文献   

The Jet Driven Motions in the Narrow Line Region of NGC 1068     

David J. Axon  A. Marconi  F.D. Macchetto  A. Capetti  Andrew Robinson 《Astrophysics and Space Science》1997,248(1-2):69-77

We have obtained HST FOC f/48 long-slit spectroscopy of the central 2 arcseconds of the Narrow Line Region of NGC 1068 between 3500-5400\OA with a spectral resolution of 1.78\OA/pixel. At a spatial scale of 0″.0287 per pixel these data provide an order of magnitude improvement in resolution over previous ground based spectra and allow us to trace the interaction between the radio jet and the gas in the NLR. Our results show that, within ±0″.5 of the radio-jet the emission lines are split into two components whose velocity separation is 1500 km s-1. The emission line structure is reminiscent of that seen previously around the jet of 3C120. Furthermore, this material enveloping the radio-jet is in a much higher ionization state than that of the surrounding NLR gas. The highest excitation is coincident with the jet axis where emission in the coronal line of [FeVII] λ3769\OA is detected but where [OII] λ3727 \OA is depressed. These results imply that we are witnessing a cocoon of hot gas in expansion around the radio-jet created by its interaction with the gas, and that these shocks are sufficiently fast, at least ± km s-1, that they are creating localized ionization effects. This revised version was published online in July 2006 with corrections to the Cover Date.  相似文献   

Strong, Variable Circular Polarization in PKS 1519–273     

Jean-Pierre Macquart  Lucyna Kedziora-Chudczer  David Jauncey  David Rayner 《Astrophysics and Space Science》2001,277(1-2):135-138

It is found that velocity shear enables the extraction of kinetic energy from the background flow by Dust-Acoustic waves. It is also shown that the velocity shear leads to the appearance of a new mode of the dust particles collective behaviour, called shear dust vortices. This revised version was published online in July 2006 with corrections to the Cover Date.  相似文献   

ALH84001, a cumulate orthopyroxenite member of the martian meteorite clan     

David W. Mittlefehldt 《Meteoritics & planetary science》1994,29(2):214-221

Abstract— ALH84001, originally classified as a diogenite, is a coarse-grained, cataclastic, orthopyroxenite meteorite related to the martian (SNC) meteorites. The orthopyroxene is relatively uniform in composition, with a mean composition of Wo_3.3En_69.4Fs_27.3. Minor phases are euhedral to subhedral chromite and interstitial maskelynite, An_31.1Ab_63.2Or_5.7, with accessory augite, Wo_42.2En_45.1Fs_12.7, apatite, pyrite and carbonates, Cc_11.5Mg_58.0Sd_29.4Rd_1.1. The pyroxenes and chromites in ALH84001 are similar in composition to these phases in EETA79001 lithology A megacrysts but are more homogeneous. Maskelynite is similar in composition to feldspars in the nakhlites and Chassigny. Two generations of carbonates are present, early (pre-shock) strongly zoned carbonates and late (post-shock) carbonates. The high Ca content of both types of carbonates indicates that they were formed at moderately high temperature, possibly ～700 °C. ALH84001 has a slightly LREE-depleted pattern with La 0.67x and Lu 1.85x CI abundances and with a negative Eu anomaly (Eu/Sm 0.56x CI). The uniform pyroxene composition is unusual for martian meteorites, and suggests that ALH84001 cooled more slowly than did the shergottites, nakhlites or Chassigny. The nearly monomineralic composition, coarse-grain size, homogenous orthopyroxene and chromite compositions, the interstitial maskelynite and apatite, and the REE pattern suggest that ALH84001 is a cumulate orthopyroxenite containing minor trapped, intercumulus material.  相似文献