活动星系核与类星体中致密天体的形成与并合：伽玛爆发与引力辐射     

王建民 《紫金山天文台台刊》1999,18(3):271-273

频繁的超新星爆发可用以解释活动星系核与类星体的超高金属丰度。星团中的恒星与吸积盘相互作用导致致密天体中子星和黑洞的形成率很高,这些致密天体与红巨星很容易形成双星系统,而后形成（ＮＳ／ＢＨ,ＮＳ／ＢＨ） 双星由于引力辐射最终导致并合而形成伽玛射线爆发。我们估计了伽玛射线爆的爆发频率,发现与观测相符。  相似文献   

区域重力场相对基准的建立   总被引：2，自引：1，他引：1  

孙少安  项爱民 《大地测量与地球动力学》1999,19(1):78-81

针对地震系统各区域重力网的现状,提出了一种在没有绝对重力测量资料的情况下,利用网区多年积累的观测资料,建立区域重力场相对基准的方法。实验证明,采用该方法建立的区域重力场相对基准,精度优于５０ｎｍ·ｓ－２,不仅有利于地震重力前兆信息的提取,而且能优化和评定区域重力网的质量,标定和检测重力仪参数及其变化。  相似文献   

Special Solutions in a Simplified Restricted Three-Body Problem with Gravitational Radiation Taken into Account     

V. A. Brumberg 《Celestial Mechanics and Dynamical Astronomy》2003,85(3):269-291

The distinctive feature of the relativistic restricted three-body problem within the c ^–5 order of accuracy (2 post-Newtonian approximation) is the presence of the gravitational radiation. To simplify the problem the motion of the massive binary components is assumed to be quasi-circular. In terms of time these orbits have linearly changing radii and quadratically changing phase angles. By substituting this motion into the Newtonian-like equations of motion one gets the quasi-Newtonian restricted quasi-circular three-body problem sufficient to take into account the main indirect perturbations caused by the binary radiation terms. Such problem admits the Lagrange-like quasi-libration solutions and rather simple quasi-circular orbits lying at large distance from the binary.  相似文献   

顾及地球引力摄动的卫星和卫星星下点位置计算     

查明 《测绘科学与工程》2006,26(1):44-45,40

本文叙述了顾及地球引力摄动的卫星化置计算方法；利用天球坐标系与地球坐标系之间的坐标变换关系，给出了由卫星位置计算卫星星下点位置的严密计算公式。  相似文献   

Thermochronology and exhumation rates of granitic intrusions at Mesa Central,Mexico     

Angel F. Nieto-Samaniego  María de Jesús Paulina Olmos-Moya  Gilles Levresse  Susana A. Alaniz-Alvarez  Fanis Abdullin  Alexis del Pilar-Martínez 《International Geology Review》2020,62(3):311-319

ABSTRACT

The Mesa Central of Mexico (MC) is an elevated plateau located 2000 m above sea level in central Mexico, where intrusions outcrop that register the history of exhumation-erosion occurring during the Late Cretaceous-Paleogene. The tectonic history of the region records formation of the Late Cretaceous-Paleogene ‘Mexican orogen’; this was followed by extension of the entire region and several plutons were then exhumed. The age and magnitude of the crustal uplift and erosion occurring during exhumation has not been addressed to date. Therefore, this study reports the crystallization and cooling ages of two plutons, the Tesorera Granodiorite and the Comanja Granite, and estimates their emplacement depths. Based on these data, the exhumation age of the Tesorera Granodiorite is estimated to be between ~73 Ma and ~63 Ma at an exhumation rate of ~528 m/m. y. and that of the Comanja Granite is 52 Ma and 48 Ma at an exhumation rate of ~2500 m/m. y. Exhumation-erosion event of the Tesorera Granodiorite was located on the trace of the San Luis-Tepehuanes Fault System and that of the Comanja Granite on the a trace of the El Bajío Fault System. Furthermore, the high exhumation rate in the Comanja Granite suggests that gravitational collapse played an important role during exhumation.  相似文献   

The complex gravitational lens system B1933+503     

C. M. Sykes  I. W. A. Browne  N. J. Jackson  D. R. Marlow  S. Nair  P. N. Wilkinson  R. D. Blandford  J. Cohen  C. D. Fassnacht  D. Hogg  T. J. Pearson  A. C. S. Readhead  D. S. Womble  S. T. Myers  A. G. de Bruyn  M. Bremer  G. K. Miley  & R. T. Schilizzi 《Monthly notices of the Royal Astronomical Society》1998,301(2):310-314

We report the discovery of the most complex arcsec-scale radio gravitational lens system yet known. B1933+503 was found during the course of the CLASS survey and MERLIN and VLA radio maps reveal up to 10 components. Four of these are compact and have flat spectra; the rest are more extended and have steep spectra. The background lensed object appears to consist of a flat-spectrum core (quadruply imaged) and two compact 'lobes' symmetrically disposed relative to the core. One of the lobes is quadruply imaged while the other is doubly imaged. An HST observation of the system with the WFPC2 shows a galaxy with an axial ratio of 0.5, but none of the images of the background object is detected. A redshift of 0.755 has been measured for the lens galaxy.  相似文献   

Modelling the 10-image lensed system B1933+503     

S. Nair 《Monthly notices of the Royal Astronomical Society》1998,301(2):315-322

A gravitational lens model is presented for the newly discovered 10-image system B1933+503. The underlying object, revealed by modelling, is a triple radio source on the scale of a couple of hundred mas that is well-aligned along the line of sight with a foreground and somewhat flattened lensing galaxy, the orientation and location of which match those of an observed galaxy, known to be at a redshift of 0.755. Uncertainties in the modelling are obtained by a Monte Carlo exercise. Observational tests of the lens model are proposed, and the time delays between various pairs of images are determined, as the core of the source is known to be significantly variable. Future observations of the lens hold the key to using B1933+503 to constrain Hubble's constant. Despite the absence of a source redshift, the utility of the system as a probe of the structure of the lens galaxy is unparalleled as it provides a surfeit of easily identifiable constraints for modelling the system.  相似文献   

Constraining the Mass Distribution of Cluster Galaxies by Weak Lensing     

Bernhard Geiger  & Peter Schneider 《Monthly notices of the Royal Astronomical Society》1998,295(3):497-510

Analysing the weak lensing distortions of the images of faint background galaxies provides a means to constrain the average mass distribution of cluster galaxies and potentially to test the extent of their dark matter haloes as a function of the density of their environment. The observable image distortions are a consequence of the interplay between the effects of a global cluster mass distribution and the perturbations resulting from individual cluster galaxies. Starting from a reconstruction of the cluster mass distribution with conventional techniques, we apply a maximum likelihood method to infer the average properties of an ensemble of cluster galaxies. From simulations this approach is found to be reliable as long as the galaxies including their dark matter haloes only contribute a small fraction to the total mass of the system. If their haloes are extended, the galaxies contain a substantial mass fraction. In this case our method is still applicable in the outer regions of clusters, where the surface mass density is low, but yields biased estimates of the parameters describing the mass profiles of the cluster galaxies in the central part of the cluster. In that case it will be necessary to resort to more sophisticated strategies by modelling cluster galaxies and an underlying global mass distribution simultaneously. We conclude that galaxy–galaxy lensing in clusters provides a unique means to probe the presence and extent of dark haloes of cluster galaxies.  相似文献   

Surface potential and gravity changes due to internal dislocations in a spherical earth—II. Application to a finite fault     

Wenke Sun  & Shuhei Okubo 《Geophysical Journal International》1998,132(1):79-88

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A complete infrared Einstein ring in the gravitational lens system B1938 + 666     

L.J. King  N. Jackson  R.D. Blandford  M.N. Bremer  I.W.A. Browne  A.G. de Bruyn  C. Fassnacht  L. Koopmans  D. Marlow  P.N. Wilkinson 《Monthly notices of the Royal Astronomical Society》1998,295(2):L41-L44

We report the discovery, using NICMOS on the Hubble Space Telescope , of an arcsec-diameter Einstein ring in the gravitational lens system B1938+666. The lensing galaxy is also detected, and is most likely an early-type galaxy. Modelling of the ring is presented and compared with the radio structure from MERLIN maps. We show that the Einstein ring is consistent with the gravitational lensing of an extended infrared component, centred between the two radio components.  相似文献