The impact and rotational light curves of Comet 9P/Tempel 1

UVES and HIRES high-resolution spectra of Comet 9P/Tempel 1 are used to investigate the impact and rotational light curves of various species with a view toward building a simple model of the distribution and activity of the sources. The emission by OH, NH, CN, C₃, CH, C₂, NH₂, and OI, are analyzed, as well as the light scattered by the dust. It is found that a simple model reproduces fairly well the impact light curves of all species combining the production of the observed molecules and the expansion of the material throughout the slit. The impact light curves are consistent with velocities of 400-600 m/s. Their modeling requires a three-step dissociation sequence “Grand-Parent → Parent → Daughter” to produce the observed molecules. The rotational light curve for each species is explained in terms of a single model with three sources. The dust component can however not easily be explained that way.     

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X-ray Spectroscopy of Dips of Cir X-1

We present X-ray spectral analyses of the low-mass X-ray binary Cir X-1 dur- ing X-ray dips,using the Rossi X-ray Timing Explorer(RXTE)data.Each dip was divided into several segments,and the spectrum of each segment was fitted with a three-component blackbody model,in which the first two components are affected by partial covering and the third one is unaffected.A Gaussian emission line is also included in the spectral model to represent the Fe Kαline at～6.4 keV.The fitted temperatures of the two partially covered components are about 2 keV and 1 keV,while the uncovered component has a temperature of～0.5-0.6 keV.The equivalent blackbody emission radius of the hottest component is the smallest and that of the coolest component is the largest.During the dips the fluxes of the two hot components are linearly correlated,while that of the third component does not show any significant variation.The Fe line flux remains constant,within the errors,during the short dips.However,during the long dips the line flux varies significantly and is positively correlated with the fluxes of the two hot components.These results suggest:(1)that the tem- perature of the X-ray emitting region decreases with radius,(2)that the Fe Kαline emitting region is close to the hot continuum emitting region,and(3)that the size of the Fe line emit- ting region is larger than that of the obscuring matter causing the short dips but smaller than the region of that causing the long dips.     

The internal structure of Jupiter family cometary nuclei from Deep Impact observations: The “talps” or “layered pile” model

We consider the hypothesis that the layering observed on the surface of Comet 9P/Tempel 1 from the Deep Impact spacecraft and identified on other comet nuclei imaged by spacecraft (i.e., 19P/Borrelly and 81P/Wild 2) is ubiquitous on Jupiter family cometary nuclei and is an essential element of their internal structure. The observational characteristics of the layers on 9P/Tempel 1 are detailed and considered in the context of current theories of the accumulation and dynamical evolution of cometary nuclei. The works of Donn [Donn, B.D., 1990. Astron. Astrophys. 235, 441-446], Sirono and Greenberg [Sirono, S.-I., Greenberg, J.M., 2000. Icarus 145, 230-238] and the experiments of Wurm et al. [Wurm, G., Paraskov, G., Krauss, O., 2005. Icarus 178, 253-263] on the collision physics of porous aggregate bodies are used as basis for a conceptual model of the formation of layers. Our hypothesis is found to have implications for the place of origin of the JFCs and their subsequent dynamical history. Models of fragmentation and rubble pile building in the Kuiper belt in a period of collisional activity (e.g., [Kenyon, S.J., Luu, J.X., 1998. Astron. J. 115, 2136-2160; 1999a. Astron. J. 118, 1101-1119; 1999b. Astrophys. J. 526, 465-470; Farinella, P., Davis, D.R., Stern, S.A., 2000. In: Mannings, V., Boss, A.P., Russell, S.S. (Eds.), Protostars and Planets IV. Univ. of Arizona Press, Tucson, pp. 1255-1282; Durda, D.D., Stern, S.J., 2000. Icarus 145, 220-229]) following the formation of Neptune appear to be in conflict with the observed properties of the layers and irreconcilable with the hypothesis. Long-term residence in the scattered disk [Duncan, M.J., Levison, H.F., 1997. Science 276, 1670-1672; Duncan, M., Levison, H., Dones, L., 2004. In: Festou, M., Keller, H.U., Weaver, H.A. (Eds.), Comets II. Univ. of Arizona Press, Tucson, pp. 193-204] and/or a change in fragmentation outcome modeling may explain the long-term persistence of primordial layers. In any event, the existence of layers places constraints on the environment seen by the population of objects from which the Jupiter family comets originated. If correct, our hypothesis implies that the nuclei of Jupiter family comets are primordial remnants of the early agglomeration phase and that the physical structure of their interiors, except for the possible effects of compositional phase changes, is largely as it was when they were formed. We propose a new model for the interiors of Jupiter family cometary nuclei, called the talps or “layered pile” model, in which the interior consists of a core overlain by a pile of randomly stacked layers. We discuss how several cometary characteristics—layers, surface texture, indications of flow, compositional inhomogeneity, low bulk density low strength, propensity to split, etc., might be explained in terms of this model. Finally, we make some observational predictions and suggest goals for future space observations of these objects.     

Nuclear spin temperature of ammonia in Comet 9P/Tempel 1 before and after the Deep Impact event

The Deep Impact mission succeeded in excavating inner materials from the nucleus of Comet 9P/Tempel 1 on 2005 July 04 (at 05:52 UT). Comet 9P/Tempel 1 is one of Jupiter family short period comets, which might originate in the Kuiper belt region in the solar nebula. In order to characterize the comet and to support the mission from the ground-based observatory, optical high-dispersion spectroscopic observations were carried out with the echelle spectrograph (UVES) mounted on the 8-m telescope VLT (UT2) before and after the Deep Impact event. Ortho-to-para abundance ratios (OPRs) of cometary ammonia were determined from the NH₂ emission spectra. The OPRs of ammonia on July 3.996 UT and 4.997 UT were derived to be 1.28±0.07 (nuclear spin temperature: Tspin=24±2 K) and 1.26±0.08 (Tspin=25±2 K), respectively. There is no significant change between before and after the impact. Actually, most materials ejected from the impact site could have moved away from the nucleus on July 4.997 UT, about 17 h after the impact. However, a small fraction of the ejected materials might remain in the slit of UVES instrument at that time because an excess of about 20% in the NH₂ emission flux is observed above the normal activity level was found [Manfroid, J., Hutsemékers, D., Jehin, E., Cochran, A.L., Arpigny, C., Jackson, W.M., Meech, K.J., Schulz, R., Zucconi, J.-M., 2007. Icarus. This issue]. If the excess of NH₂ on July 04.997 UT was produced from icy materials excavated by the Deep Impact, then an upper-limit of the ammonia OPR would be 1.75 (Tspin>17 K) for those materials. On the other hand, the OPR of ammonia produced from the quiescent sources was similar to that of the Oort cloud comets observed so far. This fact may imply that physical conditions where cometary ices formed were similar between Comet 9P/Tempel 1 and the Oort cloud comets.     

Determination of Platinum-Group Elements and Forty Two Other Elements in Two Candidate Danish Cretaceous-Tertiary Boundary Clay Reference Materials by INAA, ENAA and RNAA

Ruthenium, rhodium, palladium, osmium, iridium and platinum (PGEs) and forty two other elements in two candidate geological Cretaceous-Tertiary boundary clay reference materials taken from the Fish Clay, Stevns Klint, Denmark, were determined by a combination of neutron activation analysis (NAA) consisting of instrumental, epithermal and radiochemical NAA with or without nickel sulfide fire assay preconcentration. The accuracy of the experimental values was assessed by the comparative analysis of the certified reference materials.     

Precise Determination of Rubidium in Geological Reference Materials by ID-TIMS and WD-XRF: A Discussion for the Basalt BIR-1

Data were obtained for rubidium in six geological reference materials by isotopic dilution thermal ionisation mass spectrometry (ID-TIMS) and wavelength dispersive X-ray fluorescence spectrometry (WD-XRF). The results found by one technique compare very well with the other within the respective analytical uncertainties and are also in good agreement with data from previously published values. The particular case of low Rb determinations in reference sample BIR-1 is discussed.     

长春地震台大震速报震级偏差研究

本次研究选用了本台 2 0 0 0年全年的速报地震资料 ,重新测算了DK 1地震仪各分向记录的面波震级 ,并以《中国地震速报台网观测报告》给出的震级为标准震级 ,进行了震级偏差统计分析。研究结果表明 ,以长春台DK 1地震仪水平向高倍档记录测算的面波震级平均偏低 0 1 1 ,标准误差为± 0 2 1 ;以水平向低倍档记录测算的面波震级平均偏高 0 1 0 ,标准误差为± 0 2 0 ;以垂直向记录测算的面波震级平均偏低 0 2 4,标准误差为± 0 2 6。通过对统计结果的全面分析 ,分别给出了长春台DK 1地震仪水平向高低倍档和垂直向记录测算面波震级的台站校正值。     

聊古一井数字化氡观测资料的分析与应用

对聊古一井SD－3A数字化氡观测资料的变化特征进行了分析，与该井原有的模拟观测资料进行了对比研究，并对数字化氡观测资料的应用与分析方法进行了探讨。认为尽管SD－3A自动测氡仪所测为逸出氡与模拟观测溶解氡的物理量有所不同，但两具有基本一致的变化趋势，且数字化氡具有较强的映震能力。     

核废物处置场岩体断裂的遥感分析

本文利用ＴＭ和ＳＩＲ－Ａ遥感图像对甘肃北山区４个预选的核废物处置场址的岩体断裂进行了解释和编图。并运用线性构造统计分析方法，对岩体断裂发育程度进行了统计分析。