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991.
The 4.45 m-thick pure ice lens have been discovered firstly at depth from 19.81 -24.26 m in the bore No.6, which locates in north bank of the Ngoring Lake. In source region of the Huanghe (Yellow) River, 14C dating, X -ray diffraction, pollen analysis, micropalaeontology, chemical components, environmental isotope 2H, 3H, 18O and freezing point of the ice and water samples from the bore have been tested and microorganism in the ice have been also appraised with microscope. Combined with the research on geomorphy and Quaternary around the lake, the ice lens are determined as a kind of deep-buried lake ice, formed in 35,030-45,209 yr.B.P., and annual mean air temperature was about -10℃ during that time. 相似文献
992.
993.
Alessandro Marconi Roberto Maiolino Romain G. Petrov 《Astrophysics and Space Science》2003,286(1-2):245-254
Interferometry in the optical and near infrared has so far played a marginal role in Extragalactic Astronomy. Active Galactic
Nuclei are the brightest and most compact extragalactic sources, nonetheless only a very limited number could be studied with
speckle interferometry and none with long baseline interferometry. The VLTI will allow the study of moderately faint extragalactic
objects with very high spatial resolution thus opening a new window on the universe. With this paper we focus on three scientific
cases to show how AMBER and MIDI can be used to tackle open issues in extragalactic astronomy.
This revised version was published online in July 2006 with corrections to the Cover Date. 相似文献
994.
Gerhard Hensler Daniel Tschöke Dominik Bomans Alessandro Boselli 《Astrophysics and Space Science》2003,284(2):467-470
Observations of the Virgo Cluster galaxy NGC 4569 in soft X-rays and in Hα reveal both an asymmetrically distributed hot gaseous
halo and a giant filament of diffuse emission, respectively, extending from the same side of the disk, the latter one to at
least 8.8 kpc. A deep longslit spectrum along the filament shows velocities systematically different from the systemic velocity
of NGC 4569. With the inclination of the disk one can determine the Hα spur as a giant outflow in NGC 4569.
This revised version was published online in August 2006 with corrections to the Cover Date. 相似文献
995.
A Fundamental Plane of black hole activity 总被引:1,自引:0,他引:1
996.
In-situ particle acceleration in extragalactic radio hot spots: observations meet expectations 总被引:1,自引:0,他引:1
G. Brunetti K.-H. Mack M. A. Prieto S. Varano 《Monthly notices of the Royal Astronomical Society》2003,345(3):L40-L44
We discuss, in terms of particle acceleration, the results from optical VLT observations of hot spots associated with radio galaxies. On the basis of observational and theoretical grounds, the following is shown. (i) Relatively low radio-radio power hot spots are the optimum candidates for being detected at optical waves. This is supported by an unprecedented optical detection rate of 70 per cent out of a sample of low radio power hot spots. (ii) The shape of the synchrotron spectrum of hot spots is mainly determined by the strength of the magnetic field in the region. In particular, the break frequency, related to the age of the oldest electrons in the hot spots, is found to increase with decreasing synchrotron power and magnetic field strength. Both observational results are in agreement with an in-situ particle acceleration scenario. 相似文献
997.
998.
999.
本文通过太阳活动区光球和色球速度场和磁场观测资料,讨论了黑子活动区附近流场的精细结构,论述了太阳大气中物质的流动呈纤维结构,以及速度场纤维与磁场,色球纤维和网络结构之间的关系。 相似文献
1000.