共查询到16条相似文献,搜索用时 109 毫秒
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本文列举了最近以来,光学天文、VLBI和LLR等技术对主章动常数的测量结果,结果表明对国际天文学联合会(IAU)在1982年通过的1980 IAU章动理论应予以修正。文中强调了现代天文实测工作应该在地球模型和章动理论的研究中起到更大的作用;还讨论了在实际进行主章动常数测量工作时应该注意的一些问题。 相似文献
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地球动力学扁率及其与岁差章动的关系 总被引:5,自引:0,他引:5
由岁差常数求得的日月岁差是天文学的重要参数之一,它和地球动力学扁率相联系。地球动力学扁率在章动理论的计算中也是一个重要的物理量。介绍了由不同的观测方法和模型给出的地球动力扁率值,并讨论了它也岁差的关系和对章动计算的影响。在刚体地球章动振幅的计算中,地球动力学扁率值起着尺度因子的作用,要改善刚体地球章动振幅的计算,需要修改目前的黄经总岁差值。非刚体地球章动的转换函数中所采用的简正模和常数都直接或间接地依赖地球动力学扁率值。在IAU1980章动理论中,计算刚体地球章动振幅所使用的地球动力学扁率值计算转换函数中简正模频率和常数所使用的地球动力学扁率值并不一致。随着观测和计算精度的提高,地球动力学扁率值的不一致将影响章动振幅的计算。在建立刚体地球章地动理论中,如何解释地球动力学扁率值的差异,如何选取地球动力学扁率值,还有待进一步的研究。 相似文献
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章动序列的不准确引起春分点和黄赤交角的变化,直接影响到射电源的赤经、赤纬。利用IRIS网五天一组的VLBI观测资料,我们解算了定组观测的13颗射电源的赤经、赤纬,从射电源的位置残差解算出黄经章动和交角章动的改正,并估算了章动周年项(365.3天)和半年项(182.6天)的系数改正及自由核章动的振幅。 相似文献
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本文利用Hamilton方法研究弹性地球自转运动,采用地球模型PREM参数,给出了形状轴的章动序列.结果表明我们的方法是可行的,计算是可靠的.弹性地幔对地球章动的影响仅在毫角秒量级上,它相对液核对地球竟动的影响要小得多. 相似文献
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本文从爱因斯坦场方程的解开始,严格而细致地论证了相对论岁差和章动的起源,推导了测地、Lense-Thirring、Thomas岁差章动和黄极的相对论进动的理论表达式。 相似文献
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月球物理天平动对环月轨道器运动的影响 总被引:3,自引:0,他引:3
月球物理天平动是月球赤道在空间真实的摆动,会导致月球引力场在空间坐标系中的变化,从而引起环月轨道器(以下称为月球卫星)的轨道变化,这与地球的岁差章动现象对地球卫星轨道的影响类似.采用类似对地球岁差章动的处理方法,讨论月球物理天平动对月球卫星轨道的影响,给出相应的引力位的变化及卫星轨道的摄动解,清楚地表明了月球卫星轨道的变化规律,并和数值解进行了比对,从定性和定量方面作一讨论. 相似文献
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Juan Getino José M. Ferrándiz 《Monthly notices of the Royal Astronomical Society》1999,306(4):L45-L49
In this letter we present the first accurate analytical nutation series, deduced from the Hamiltonian theory by the authors. They provide the highest accuracy ever obtained by any analytical nutation series, since the deviation in CEP (celestial ephemeris pole) offsets with respect to that of the IERS Conventions 1996 is kept below 1 mas in the time domain, in spite of still lacking ocanic corrections. 相似文献
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G. B. Hobbs R. T. Edwards R. N. Manchester 《Monthly notices of the Royal Astronomical Society》2006,369(2):655-672
Contemporary pulsar-timing experiments have reached a sensitivity level where systematic errors introduced by existing analysis procedures are limiting the achievable science. We have developed tempo2 , a new pulsar-timing package that contains propagation and other relevant effects implemented at the 1-ns level of precision (a factor of ∼100 more precise than previously obtainable). In contrast with earlier timing packages, tempo2 is compliant with the general relativistic framework of the IAU 1991 and 2000 resolutions and hence uses the International Celestial Reference System, Barycentric Coordinate Time and up-to-date precession, nutation and polar motion models. tempo2 provides a generic and extensible set of tools to aid in the analysis and visualization of pulsar-timing data. We provide an overview of the timing model, its accuracy and differences relative to earlier work. We also present a new scheme for predictive use of the timing model that removes existing processing artefacts by properly modelling the frequency dependence of pulse phase. 相似文献
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Z. Abraham D. Falceta-Gonçalves 《Monthly notices of the Royal Astronomical Society》2010,401(1):687-694
It is believed that η Carinae is actually a massive binary system, with the wind–wind interaction responsible for the strong X-ray emission. Although the overall shape of the X-ray light curve can be explained by the high eccentricity of the binary orbit, other features like the asymmetry near periastron passage and the short quasi-periodic oscillations seen at those epochs have not yet been accounted for. In this paper we explain these features assuming that the rotation axis of η Carinae is not perpendicular to the orbital plane of the binary system. As a consequence, the companion star will face η Carinae on the orbital plane at different latitudes for different orbital phases and, since both the mass-loss rate and the wind velocity are latitude dependent, they would produce the observed asymmetries in the X-ray flux. We were able to reproduce the main features of the X-ray light curve assuming that the rotation axis of η Carinae forms an angle of 29°± 4° with the axis of the binary orbit. We also explained the short quasi-periodic oscillations by assuming nutation of the rotation axis, with an amplitude of about 5° and a period of about 22 days. The nutation parameters, as well as the precession of the apsis, with a period of about 274 years, are consistent with what is expected from the torques induced by the companion star. 相似文献
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夏一飞 《紫金山天文台台刊》2000,19(2):149-153
刚体地球章动序列和非刚体地球章动的转换函数都和地球动力学扁率有关。IAU1980章动理论中采用了一个不一致的地球动力学扁率值,从而影响了章动振幅的计算。本文介绍了章动序列计算中地球动力学扁率的取值。由地球模型1066A或PREM得到的地球动力学扁率值比由岁差观测得到的约小1%,并且不可靠。当考虑体静力学平衡被破坏时新的地球物理模型,可得到与岁差常数相一致的地球动力学扁率值。地球动力学扁率值H=0. 相似文献
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M. G. Rochester 《Celestial Mechanics and Dynamical Astronomy》1981,24(3):231-234
A recently-published paper, concerning the effects of core-mantle coupling on the Earth's precession and nutation, is critically appraised in the light of previously-published work in astronomy and geophysics. 相似文献