Interaction between the north-eastern boundary of Sgr A East and giant molecular clouds     

Sungho Lee  Soojong Pak  Christopher J. Davis  Robeson M. Herrnstein  T. R. Geballe  Paul T. P. Ho  J. Craig Wheeler 《Monthly notices of the Royal Astronomical Society》2003,341(2):509-516

We have detected the   v = 1 → 0 S(1) (λ= 2.1218 μm)  and   v = 2 → 1 S(1) (λ= 2.2477 μm)  lines of H₂ in the Galactic Centre, in a  90 × 27 arcsec²  region between the north-eastern boundary of the non-thermal source Sgr A East, and the giant molecular cloud (GMC)  M−0.02 − 0.07  . The detected  H₂ v = 1 → 0  S(1) emission has an intensity of  1.6–21 × 10⁻¹⁸ W m⁻² arcsec⁻²  and is present over most of the region. Along with the high intensity, the large linewidths  (FWHM = 40–70 km s⁻¹)  and the  H₂ v = 2 → 1 S(1)  to   v = 1 → 0 S(1)  line ratios (0.3–0.5) can be best explained by a combination of C-type shocks and fluorescence. The detection of shocked H₂ is clear evidence that Sgr A East is driving material into the surrounding adjacent cool molecular gas. The H₂ emission lines have two velocity components at ∼+50 and  ∼0 km s⁻¹  , which are also present in the NH₃(3, 3) emission mapped by McGary, Coil & Ho. This two-velocity structure can be explained if Sgr A East is driving C-type shocks into both the  GMC M−0.02 − 0.07  and the northern ridge of McGary et al.  相似文献   

Chemical enrichment by Wolf–Rayet and asymptotic giant branch stars     

Lynnette M. Dray  Christopher A. Tout  Amanda I. Karakas  John C. Lattanzio 《Monthly notices of the Royal Astronomical Society》2003,338(4):973-989

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Physics‐based hydrologic‐response simulation: foundation for hydroecology and hydrogeomorphology     

Keith Loague  Christopher S. Heppner  Benjamin B. Mirus  Brian A. Ebel  Qihua Ran  Adrianne E. Carr  Susan H. BeVille  Joel E. VanderKwaak 《水文研究》2006,20(5):1231-1237

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The Relation between the Critical Accretion Rate of Progenitors of SNe Ia and Metallicity     

Christopher A. Tout 《中国天文和天体物理学报》2006,6(4):461-469

A carbon-oxygen white dwarf may explode in a Type Ia supernova by accreting matter from its companion via either Roche lobe overflow or from winds, but there exists a critical accretion rate of the progenitor system for the explosion. We study the relation between the critical accretion rate and the metallicity via an AGB star approach. The result indicates that the critical accretion rate depends not only on the hydrogen mass fraction and the white dwarf mass, but also on the metallicity. The effect of the metallicity is smaller than that of the white dwarf mass. We show that it is reasonable to use the model with stellar mass 1.6 M⊙for real white dwarfs.  相似文献   

Silicate absorption in heavily obscured galaxy nuclei     

Patrick F. Roche  Christopher Packham  David K. Aitken  Rachel E. Mason 《Monthly notices of the Royal Astronomical Society》2007,375(1):99-104

Spectroscopy at 8–13 μm with T-ReCS on Gemini-S is presented for three galaxies with substantial silicate absorption features, NGC 3094, NGC 7172 and NGC 5506. In the galaxies with the deepest absorption bands, the silicate profile towards the nuclei is well represented by the emissivity function derived from the circumstellar emission from the red supergiant, μ Cephei which is also representative of the mid-infrared absorption in the diffuse interstellar medium in the Galaxy. There is spectral structure near 11.2 μm in NGC 3094 which may be due to a component of crystalline silicates. In NGC 5506, the depth of the silicate absorption increases from north to south across the nucleus, suggestive of a dusty structure on scales of tens of parsecs. We discuss the profile of the silicate absorption band towards galaxy nuclei and the relationship between the 9.7-μm silicate and 3.4-μm hydrocarbon absorption bands.  相似文献   

The Hubble Deep Field North SCUBA Super-map – III. Optical and near-infrared properties of submillimetre galaxies     

Alexandra Pope  Colin Borys  Douglas Scott  Christopher Conselice  Mark Dickinson  Bahram Mobasher 《Monthly notices of the Royal Astronomical Society》2005,358(1):149-167

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Temporal constraints on the growth and decay of large-scale mobilized mud masses and implications for fluid flow mapping in sedimentary basins     

Christopher Jackson  Daniel Stoddart 《地学学报》2005,17(6):580-585

Seismic-stratigraphic analysis of the Cretaceous to succession of the Uer Terrace, North Sea seabed Basin, Norway, demonstrates that the Upper Oligocene succession has undergone large-scale mobilization of mudstone-dominated units due to the upward migration of water and associated hydrocarbons into the interval, which is in some way linked to a period of gas expulsion from adjacent deep basins. Seismic-stratigraphic analysis of units overlying the mobilized zones indicates they created positive seafloor topography during the Late Miocene implying gaseous fluids were expelled at the seabed. Loading by the overlying Pliocene succession caused the mobilized mud masses to deflate and resulted in the formation of low-relief, fault-bounded craters. The results of this study have implications for understanding the location and timing of fluid flow in sedimentary basins.  相似文献   

Critical mass transfer in double-degenerate Type Ia supernovae     

Rebecca G. Martin  Christopher A. Tout  Pierre Lesaffre 《Monthly notices of the Royal Astronomical Society》2006,373(1):263-270

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The white dwarf in AE Aqr brakes harder     

Christopher W. Mauche 《Monthly notices of the Royal Astronomical Society》2006,369(4):1983-1987

Taking advantage of the very precise de Jager et al. optical white dwarf orbit and spin ephemerides; ASCA , XMM–Newton and Chandra X-ray observations spread over 10 yr; and a cumulative 27-yr baseline, we have found that in recent years the white dwarf in AE Aqr is spinning down at a rate that is slightly faster than predicted by the de Jager et al. spin ephemeris. At the present time, the observed period evolution is consistent with either a cubic term in the spin ephemeris with     , which is inconsistent in sign and magnitude with magnetic dipole radiation losses, or an additional quadratic term with     , which is consistent with a modest increase in the accretion torques spinning down the white dwarf. Regular monitoring, in the optical, ultraviolet and/or X-rays, is required to track the evolution of the spin period of the white dwarf in AE Aqr.  相似文献   

Detection of large-scale intrinsic ellipticity–density correlation from the Sloan Digital Sky Survey and implications for weak lensing surveys     

Rachel Mandelbaum  Christopher M. Hirata  Mustapha Ishak  Uro&#; Seljak  Jonathan Brinkmann 《Monthly notices of the Royal Astronomical Society》2006,367(2):611-626

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