Proton Irradiation of Centaur,Kuiper Belt,and Oort Cloud Objects at Plasma to Cosmic Ray Energy     

Cooper  John F.  Christian  Eric R.  Richardson  John D.  Wang  Chi 《Earth, Moon, and Planets》2003,92(1-4):261-277

Times for accumulation of chemically significant dosages on icy surfaces of Centaur, Kuiper Belt, and Oort Cloud objects from plasma and energetic ions depend on irradiation position within or outside the heliosphere. Principal irradiation components include solar wind plasma ions, pickup ions from solar UV ionization of interstellar neutral gas, energetic ions accelerated by solar and interplanetary shocks, including the putative solar wind termination shock, and galactic cosmic ray ions from the Local Interstellar Medium (LISM). We present model flux spectra derived from spacecraft data and models for eV to GeV protons at 40 AU, a termination shock position at 85 AU, and in the LISM. Times in years to accumulate dosages ～100 eV per molecule are computed from the spectra as functions of sensible surface depth less than one centimeter at unit density.The collisional resurfacing model of Luu and Jewitt is reconsidered in thecontext of depth-dependent dosage rates from plasma, suprathermal,and higher energy protons, and global exposure, by micrometeoroiddust grain impacts, of moderately irradiated red material below athin crust of heavily irradiated neutral material. This material should be more visible on dynamically `cold’ objects in the ～40 AU region.  相似文献   

A search for the optical and near-infrared counterpart of the accreting millisecond X-ray pulsar XTE J1751−305     

P. G. Jonker  G. Nelemans  Z. Wang  A. K. H. Kong  D. Chakrabarty  M. Garcia  P. J. Groot  M. van der Klis  T. Kerr  B. Mobasher  M. Sullivan  T. Augusteijn  B. W. Stappers  P. Challis  R. P. Kirshner  J. Hjorth  A. Delsanti 《Monthly notices of the Royal Astronomical Society》2003,344(1):201-206

We have obtained optical and near-infrared images of the field of the accreting millisecond X-ray pulsar XTE J1751−305. There are no stars in the 0.7-arcsec error circle (0.7 arcsec is the overall uncertainty arising from tying the optical and X-ray images and from the intrinsic uncertainty in the Chandra X-ray astrometric solution). We derive limiting magnitudes for the counterpart of   R > 23.1, I > 21.6, Z > 20.6, J > 19.6  and   K > 19.2  . We compare these upper limits with the magnitudes one would expect for simple models for the possible donor stars and the accretion disc subject to the reddening observed in X-rays for XTE J1751−305 and when put at the distance of the Galactic Centre (8.5 kpc). We conclude that our non-detection does not constrain any of the models for the accretion disc or possible donor stars. Deep, near-infrared images obtained during quiescence will, however, constrain possible models for the donor stars in this ultracompact system.  相似文献   

商丹断裂构造特征及其演化     

王全庆 《地球科学与环境学报》1992,(1)

商丹断裂带是北秦岭加里东造山带与中秦岭海西造山带的分界断裂,由韧性剪切应变带、逆冲推覆构造带、地堑断陷带及其所夹持的岩块、岩片、构造岩、褶曲等多种地质体组合成复杂的断裂带。其演化历史至少经历晋宁期俯冲、加里东期碰撞、海西—印支期陆内俯冲、燕山期滑脱推覆和喜山期地堑断陷的复杂演化过程而形成今日所见的复杂断裂构造。  相似文献   

八家子铅锌矿区吴家屯矿床矿物特征及银赋存状态     

王树华 《国土资源》1992,(2)

八家子铅锌矿区吴家屯矿床是燕山期形成的热液充填交代脉状铅锌矿床。矿床中除铅锌矿外还伴生有银、硫、铜、锰等多种有益元素。银主要呈微粒自然银、辉银矿、金银矿、银黝铜矿、黝锑银矿、硫砷铜银矿、含碲银矿物等产出,并呈包裹体产于方铅矿、闪锌矿、黄铁矿、黄铜矿、石英等矿物中,或充填于这些矿物的裂隙及晶隙中。少部分银则以类质同象形式存在于方铅矿、黄铁矿矿物中。  相似文献   

First large urban gasfield in China was established in Chengdu     

Daxing Wang  Jinghuai Gao  Youming Li  Zhengyuan Xia  Baojiang Wang 《应用地球物理》2004,1(1):25

  相似文献   

介质横向不均匀对震后地表位移场的影响     

朱桂芝  王庆良  李辉  唐文 《大地测量与地球动力学》2003,23(4):54-59

利用三维有限元模拟两层地球模型(包括弹性层和粘弹性层)介质的横向不均匀和断层错动的复杂性对震后地表位移场的影响，其数值结果包括弹性解和粘弹性解。结果表明，震后位移场的分布特征不仅与粘弹性层的流变特性有关，还与弹性层介质的剪切模量以及断层的同震错动有关。  相似文献   

Noble gases and mineralogy of meteorites from China and the Grove Mountains,Antarctica: A 0.05 Ma cosmic ray exposure age of GRV 98004     

Silvio Lorenzetti  Yangting Lin  Daode Wang  Otto Eugster 《Meteoritics & planetary science》2003,38(8):1243-1253

Abstract— We determined the mineralogical and chemical characteristics and the He, Ne, and Ar isotopic abundances of 2 meteorites that fell in China and of 2 meteorites that were recovered by the 15th Chinese Antarctic Research Expedition. Guangmingshan (H5), Zhuanghe (H5), and Grove Mountain (GRV) 98002 (L5) yield cosmic ray exposure (CRE) ages of 68.7 ± 10.0 Ma, 3.8 ± 0.6 Ma, and 17.0 ± 2.5 Ma, respectively. These ages are within the range typically observed for the respective meteorite types. GRV 98004 (H5) had an extremely short parent body‐Earth transfer time of 0.052 ± 0.008 Ma. Its petrography and mineral chemistry are indistinguishable from other typical H5 chondrites. Only 3 other meteorites exist with similarly low CRE ages: Farmington (L5), Galim (LL6), and ALH 82100 (CM2). We show that several asteroids in Earth‐crossing orbits, or in the main asteroid belt with orbits close to an ejection resonance, are spectrally matching candidates and may represent immediate precursor bodies of meteorites with CRE ages ≤0.1 Ma.  相似文献   

Fast neutral particles as probes of the extent of Io's exosphere     

M. M. Cowee  Y-L. Wang  C. T. Russell   《Planetary and Space Science》2003,51(14-15):945

The spatial extent of ion cyclotron waves at Io has been interpreted as requiring a multistep acceleration and transport process: exospheric ions are accelerated outward (relative to Jupiter) due to the corotation electric field, neutralized due to charge exchange in the surrounding exosphere, and then reionized after traveling far across magnetic field lines, at which point they generate the waves. The trajectories of the particles away from Io are sensitive to the location of their initial ionization. This paper examines the spatial distributions of fast neutrals produced under varying conditions in order to provide constraints on the possible structure and nature of the Io exosphere. While a rapid onset of cyclotron waves at a specific location around Io can be modeled with a single, point-source region of ions, such as might occur over a volcano, the regional extent of the waves suggests multiple or distributed sources.  相似文献   

Deep Processes of Basin Evolution:A Case Study of the Southern Songliao Basin and Adjacent Area,NE China in Mesozoic-Cenozoic     

Rihui Cheng  Dongpo Wang  Linfu Xue 《东北亚地学研究》2003,(1)

1IntroductionOne of the key factors related to basin geody-namics is deep process controlling formation and evolution of sedimentary basin. Depth and tempera-ture of asthenosphere,existence of mantle plume,occurrence of mantle melting,and amounts of melts under depressurization during thinning of lithosphere are controlling factors influenced formation and characteristics of extensional basin directly (Li,1994). Rifting is probably governed by frictional forces exerted on the base of litho…  相似文献   

ANALYSIS ON THE SPATIAL DISTRIBUTION VARIATION CHARACTERISTIC OF URBAN HEAT ENVIRONMENTAL QUALITY AND ITS MECHANISM——A Case Study of Hangzhou City     

WANGWei-wu ZHULi-zhong WANGRen-chao SHIYong-jung 《中国地理科学(英文版)》2003,13(1):39-47

Urban heat environmental quality(UHEQ) is affected by the interacting of weather condition and underlying surface framework of urban area .In the last two decades,many researchers from domestic and overseas have studied many problems at the aspect of urban heat environment such as urban heat islands ,urban air temperature and their rela-tion with urban land cover,city population,air pollution etc,In the recent years,Hangzhou,acting as a center city of Zhejiang Province in China,its urbanization quantum and quantity have both changed greatly,in particular ,representing as business affairs building,resident real property and all kins of specialty market having arisen in built-up zone,Based on Landsat TM images data in 1991 and 1999,urban underlying surface temperature value and Normalized Difference Vegetation Index (NDVI) were calculated using image interpreting and supervised classification technique by remote sensing software ERDAS image 8.4,The relation model between urban underlying surface temperature (UUST )and urban air temperature was setup according to the certain correlation patten .Reference to the relational standard of assessing human comfort and other meteorology data of Hangzhou City in summer,the spatial distribution characteristic and the spatial varia-tion degree of human comfort of heat environmental quality are estimated and mapped on a middle scale,that is ,in six districts of Hangzhou City .Then the paper reveals the main characteristic of spatial variation from 1991 to 1999.Lastly,the change mechanism is analyzed and discussed from the viewpoint of city planning,construction and environmental protec-tion.  相似文献