Tracing the formation history of intermediate-age star clusters in the Small Magellanic Cloud     

Andrés E. Piatti  Ata Sarajedini  Doug Geisler  Juan Seguel  David Clark 《Monthly notices of the Royal Astronomical Society》2005,358(4):1215-1230

Colour–magnitude diagrams (CMDs) are presented for the first time for 10 star clusters projected on to the Small Magellanic Cloud (SMC). The photometry was carried out in the Washington system C and T ₁ filters allowing the determination of ages by means of the magnitude difference between the red giant clump and the main-sequence turnoff (MSTO), and metallicities from the red giant branch (RGB) locus. The clusters all have ages in the range 1.5–4 Gyr and metallicities between  −1.3 < [Fe/H] < −0.6  , with respective errors of ∼0.5 Gyr and 0.3 dex. This increases substantially the sample of intermediate-age clusters in the SMC with well-derived parameters. We combine our results with those for other clusters in the literature to derive as large and homogeneous a data base as possible (totalling 26 clusters) in order to study global effects. We find evidence for two peaks in the age distribution of SMC clusters, at ∼6.5 and 2.5 Gyr, in good agreement with previous hints involving smaller samples. The most recent peak occurs at a time that corresponds to a very close encounter between the Large Magellanic Cloud (LMC) and the SMC according to the recent dynamical models of Bekki et al. that they used to explain the enhancement of LMC clusters with this age. It appears cluster formation may have been similarly stimulated in the SMC by this encounter as well. We also find very good agreement between cluster ages and metallicities and the prediction from a bursting model from Pagel and Tautvaišienė with a burst that occurred 3 Gyr ago. These two lines of evidence together favour a bursting cluster formation history as opposed to a continuous one for the SMC.  相似文献   

Globular clusters as tracers of stellar bimodality in elliptical galaxies: the case of NGC 1399     

Juan C. Forte  Favio Faifer  Doug Geisler 《Monthly notices of the Royal Astronomical Society》2005,357(1):56-68

  相似文献   

Transport Systems, Policy and Planning: A Geographical Approach     

Doug C. Johnston 《New Zealand geographer》1997,53(1):63-64

  相似文献   

Back Analysis of the 2014 San Leo Landslide Using Combined Terrestrial Laser Scanning and 3D Distinct Element Modelling     

Margherita Cecilia Spreafico  Mirko Francioni  Federico Cervi  Doug Stead  Gabriele Bitelli  Monica Ghirotti  Valentina Alena Girelli  Claudio Corrado Lucente  Maria Alessandra Tini  Lisa Borgatti 《Rock Mechanics and Rock Engineering》2016,49(6):2235-2251

  相似文献   

Storm Surges in the Strait of Georgia Simulated with a Regional Model     

Nancy Soontiens  Susan E. Allen  Doug Latornell  Kate Le Souëf  Idalia Machuca  Jean-Philippe Paquin 《大气与海洋》2016,54(1):1-21

The Strait of Georgia is a large, semi-enclosed body of water between Vancouver Island and the mainland of British Columbia connected to the Pacific Ocean via Juan de Fuca Strait at the south and Johnstone Strait at the north. During the winter months, coastal communities along the Strait of Georgia are at risk of flooding caused by storm surges, a natural hazard that can occur when a strong storm coincides with high tide. This investigation produces storm surge hindcasts using a three-dimensional numerical ocean model for the Strait of Georgia and the surrounding bodies of water (Juan de Fuca Strait, Puget Sound, and Johnstone Strait) collectively known as the Salish Sea. The numerical model employs the Nucleus for European Modelling of the Ocean architecture in a regional configuration. The model is evaluated through comparisons of tidal elevation harmonics and storm surge with observations. Important forcing factors contributing to storm surges are assessed. It is shown that surges entering the domain from the Pacific Ocean make the most significant contribution to surge amplitude within the Strait of Georgia. Comparisons between simulations and high-resolution and low-resolution atmospheric forcing further emphasize that remote forcing is the dominant factor in surge amplitudes in this region. In addition, local wind patterns caused a slight increase in surge amplitude on the mainland side of the Strait of Georgia compared with Vancouver Island coastal areas during a major wind storm on 15 December 2006. Generally, surge amplitudes are found to be greater within the Strait of Georgia than in Juan de Fuca Strait.  相似文献   

Tips and tricks in designing management procedures   总被引：2，自引：2，他引：2  

Rademeyer  Rebecca A.; Plaganyi  Eva E.; Butterworth  Doug S. 《ICES Journal of Marine Science》2007,64(4):618-625

  相似文献   

Sensitivity of AUV added mass coefficients to variations in hull and control plane geometry     

Doug Perrault  Neil Bose  Siu O&#x;Young  Christopher D. Williams 《Ocean Engineering》2003,30(5):404-671

The sensitivity of the added mass coefficients of a typical autonomous underwater vehicle (AUV) to changes in geometric parameters was investigated. Qualitative deductions were made concerning the effect of geometric variations. Then the added mass coefficients for several configurations of body geometry were generated for the Canadian Self-Contained Off-the-shelf Underwater Testbed (C-SCOUT) vehicle using the computer program Estimate Submarine Added Mass (ESAM). The changes in the added mass coefficients have direct relationships to the varied parameter. The results presented here are specific to the C-SCOUT, but may be extended to similar axisymmetric bodies.  相似文献   

Assessment of wind-forcing impact on a global wind-wave model using the TOPEX altimeter     

Hui Feng  Doug Vandemark  Yves Quilfen  Bertrand Chapron  Brian Beckley 《Ocean Engineering》2006,33(11-12):1431-1461

The study presents assessment of an operational wave model (Wavewatch III), focusing upon the model sensitivity to wind-forcing products. Four wind fields are used to drive the model, including the NCEP/NCAR reanalysis and three other products that assimilate various satellite wind measurements having high spatial resolution, including the QuikSCAT scatterometer. Three wave field statistics: significant wave height, mean zero-crossing wave period, and mean square slope are compared with collocated TOPEX altimeter derivatives to gauge the relative skill of differing wind-forced model runs, as well as to demonstrate an extended use of the altimeter beyond simply supplying wave height for wave model validation and assimilation. Results suggest that model output is critically sensitive to choice of the wind field product. Higher spatial resolution in the wind fields does lead to improved agreement for the higher-order wave statistics.  相似文献   

Concentration, spin and shape of dark matter haloes: scatter and the dependence on mass and environment     

Andrea V. Macciò  Aaron A. Dutton  Frank C. van den Bosch  Ben Moore  Doug Potter  Joachim Stadel 《Monthly notices of the Royal Astronomical Society》2007,378(1):55-71

  相似文献   

New Zealand Journal of Marine and Freshwater Research Dec 2010     

Doug Mountfort 《新西兰海洋与淡水研究杂志》2013,47(4)

  相似文献