��������ϵ��GNSS�����������ת�������о�

??GNSS??????????У??轫GNSS?????????????????????????????????????????GNSS???????????????????????????????????????????????????????????????????????????????????????????????????????????????е???????????????????????е????λ???ó????????????????????????????????????????????????????????????????о???GNSS????????????????????????????????????????????????????????????????????????????????????????????????????????????     

基于GPS速度场的云南地壳应力积累特征分析

利用2009~2015年的GPS水平运动速度场数据,解算云南地区的地壳应变场,在红河断裂与曲江断裂选取两个GPS剖面,计算并分析两个断裂的应变积累特征。结果显示：1）红河、曲江、小江等多个主要断裂应变场存在张、压交替的时空演化特征,近期曲江断裂南段表现为东西向拉张,红河断裂北段东西向拉张量值较大,约12.0×10-8/a,云南南部主要表现为NNE向的压性变化;2）从GPS剖面看,红河、曲江断裂在两个方向上均显示右旋走滑与拉张的变化特征,从量值上看,红河断裂北段运动速率较大,约8.90 mm/a。     

Eruption of an Active-Region Filament Driven by an Emerging Bipole

1 INTRODUCTION Filaments are cool, dense material suspended in the hot, tenuous corona. It is widely accepted that the global magnetic field surrounding the filaments plays a key role in their formation, structure and stability (Tandberg-Hanssen1995). Fil…     

Planetary,solar and astrophysical relativistic electrons: Common energization mechanisms?

Direct observations or deduced analysis indicate clearly that formation of intense fluxes of relativistic electrons is an important ingredient in the evolution of numerous active magnetized plasma systems. Examples of relativistic electron energization include the recovery phase of a planetary magnetic storm, post solar flare coronal activity and the afterglow of gamma ray bursts. It is suggested that there exists a universal mechanism, which may explain electron energization at the vastly different magnetized plasma environments. The favorite configuration consists of an inhomogeneous magnetic field anchored at a given magnetic structure and excitation of whistler waves due to external injection of low-energy non-isotropic electrons. The energization proceeds as a bootstrap process due to interaction with the propagating whistler waves along the inhomogeneous magnetic field.     

The complex X-ray spectrum of the isolated neutron star RBS1223

We present a first analysis of a deep X-ray spectrum of the isolated neutron star RBS1223 obtained with XMM-Newton. Spectral data from four new monitoring observations in 2005/2006 were combined with archival observations obtained in 2003 and 2004 to form a spin-phase averaged spectrum containing 290 000 EPIC-pn photons. This spectrum shows higher complexity than its predecessors, and can be parameterised with two Gaussian absorption lines superimposed on a blackbody. The line centers, E ₂≃2E ₁, could be regarded as supporting the cyclotron interpretation of the absorption features in a field B∼4×10¹³ G. The flux ratio of those lines does not support this interpretation. Hence, either feature might be of truly atomic origin.      

The effect of magnetic fields on the formation of circumstellar discs around young stars

We present first results of our simulations of magnetic fields in the formation of single and binary stars using a recently developed method for incorporating Magnetohydrodynamics (MHD) into the Smoothed Particle Hydrodynamics (SPH) method. An overview of the method is presented before discussing the effect of magnetic fields on the formation of circumstellar discs around young stars. We find that the presence of magnetic fields during the disc formation process can lead to significantly smaller and less massive discs which are much less prone to gravitational instability. Similarly in the case of binary star formation we find that magnetic fields, overall, suppress fragmentation. However these effects are found to be largely driven by magnetic pressure. The relative importance of magnetic tension is dependent on the orientation of the field with respect to the rotation axis, but can, with the right orientation, lead to a dilution of the magnetic pressure-driven suppression of fragmentation.     

The drift model of “magnetars”

It is shown that the drift waves near the light cylinder can cause the modulation of emission with periods of order several seconds. These periods explain the intervals between successive pulses observed in AXPs, SGRs and radio pulsars with long periods. The model under consideration gives the possibility to calculate real rotation periods P of host neutron stars. It is shown that P≤1 s for the investigated objects. The magnetic fields at the surface of the neutron star are of order 10¹¹–10¹³ G and equal to the fields usual for the known radio pulsars.      

Helicoidal magneto-electron waves in interstellar molecular clouds

We investigate the evolution of the magnetic flux density in a magnetically supported molecular cloud driven by Hall and Ohmic components of the electric field generated by the flows of thermal electrons. Particular attention is given to the wave transport of the magnetic field in a cloud whose gas dynamics is dominated by electron flows; the mobility of neutrals and ions is regarded as heavily suppressed. It is shown that electromagnetic waves penetrating such a cloud can be converted into helicons – weakly damped, circularly polarized waves in which the densities of the magnetic flux and the electron current undergo coherent oscillations. These waves are interesting in their own right, because for electron magnetohydrodynamics the low-frequency helicoidal waves have the same physical significance as the transverse Alfvén waves do for a single-component magnetohydrodynamics. The latter, as is known, are considered to be responsible for the widths of molecular lines detected in dark, magnetically supported clouds. From our numerical estimates for the group velocity and the rate of dissipation of helicons it follows that a possible contribution of these waves to the broadening of molecular lines is consistent with the conditions typical of dark molecular clouds.