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81.
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83.
G. Trottet 《Space Science Reviews》1994,68(1-4):149-158
Non-thermal hard X-ray, gamma-ray and radio emission are the most direct signatures of the presence of energetic particles in the solar atmosphere. This paper lays emphasis on hard X-ray and radio imaging data, obtained during and outside flares, which reveal the sites where particles interact with the ambient medium. These observations, which provide more or less direct information on the topology and dynamics of the magnetic structures in which particles are accelerated and propagate, are discussed in the framework of the statistical flare scenario. 相似文献
84.
G. Setti G. Zamorani 《Advances in Space Research (includes Cospar's Information Bulletin, Space Research Today)》1984,3(10-12)
We review the present knowledge on the cosmological evolution of quasars, by discussing some of the recent results obtained from studies of optically selected objects. Despite the fast development of prism survey tecniques, the color selection still appears to be the best tecnique for constructing the complete samples which are necessary for statistical studies. It is shown, however, that even the best available complete samples of quasars selected on the basis of ultraviolet excess (z < 2.2) are not sufficient to univocally determine the “correct” evolutionary model. Moreover, some preliminary results suggest that the evolution law derived from quasars with mB<20 and z<2.2 can not be extrapolated to fainter magnitudes and higher redshifts. On the basis of what is known today about the optical and X-ray properties of quasars, we then discuss some of teh possible results, relevant to cosmology, which can be achieved with future coordinated optical and X-ray observations of quasars. 相似文献
85.
William V. Boynton Ann L. Sprague Sean C. Solomon Richard D. Starr Larry G. Evans William C. Feldman Jacob I. Trombka Edgar A. Rhodes 《Space Science Reviews》2007,131(1-4):85-104
The instrument suite on the MErcury Surface, Space ENvironment, GEochemistry, and Ranging (MESSENGER) spacecraft is well suited
to address several of Mercury’s outstanding geochemical problems. A combination of data from the Gamma-Ray and Neutron Spectrometer
(GRNS) and X-Ray Spectrometer (XRS) instruments will yield the surface abundances of both volatile (K) and refractory (Al,
Ca, and Th) elements, which will test the three competing hypotheses for the origin of Mercury’s high bulk metal fraction:
aerodynamic drag in the early solar nebula, preferential vaporization of silicates, or giant impact. These same elements,
with the addition of Mg, Si, and Fe, will put significant constraints on geochemical processes that have formed the crust
and produced any later volcanism. The Neutron Spectrometer sensor on the GRNS instrument will yield estimates of the amount
of H in surface materials and may ascertain if the permanently shadowed polar craters have a significant excess of H due to
water ice. A comparison of the FeO content of olivine and pyroxene determined by the Mercury Atmospheric and Surface Composition
Spectrometer (MASCS) instrument with the total Fe determined through both GRNS and XRS will permit an estimate of the amount
of Fe present in other forms, including metal and sulfides. 相似文献
86.
质子事件的爆发与太阳软X射线辐射有着很强的相关性,利用GOES卫星的1~8 (A)波段和0.5~4 (A)波段的软X射线数据,选取一些特征参量验证该相关性并应用到质子事件短期预报中.在当前质子事件传输物理机制不完全明确的情况下,在现有的预报质子事件有无的模型基础上,利用BP神经网络,根据软X射线通量水平等预测事件质子峰值通量水平,再对训练后的网络进行检验,检验预测所得结果与实际探测值误差小于一个量级,具备一定实用意义. 相似文献
87.
Coronal astronomy is by now a fairly mature discipline, with a quarter century having gone by since the detection of the first
stellar X-ray coronal source (Capella), and having benefitted from a series of major orbiting observing facilities. Serveral
observational characteristics of coronal X-ray and EUV emission have been solidly established through extensive observations,
and are by now common, almost text-book, knowledge. At the same time the implications of coronal astronomy for broader astrophysical
questions (e.g.Galactic structure, stellar formation, stellar structure, etc.) have become appreciated. The interpretation
of stellar coronal properties is however still often open to debate, and will need qualitatively new observational data to
book further progress. In the present review we try to recapitulate our view on the status of the field at the beginning of
a new era, in which the high sensitivity and the high spectral resolution provided by Chandra and SMM-Newton will address
new questions which were not accessible before.
This revised version was published online in August 2006 with corrections to the Cover Date. 相似文献
88.
R. F. Wimmer-Schweingruber 《Space Science Reviews》2006,123(1-3):471-480
This workshop summary tries to distill the key difficulties and questions in the art of (I)CME physics and strategies to address
them. (I)CMEs are multi-dimensional, multi-parameter, and multi-scale phenomena related to the solar dynamo, corona, and heliosphere.
This workshop illustrates the immense progress made in describing and modeling these spectacular energetic solar events, but
also shows clear shortcomings in our understanding of them. 相似文献
89.
T. Belloni 《Advances in Space Research (includes Cospar's Information Bulletin, Space Research Today)》2006,38(12):2801-2804
Due to the impressive amount of new data provided by the RXTE satellite in the past decade, our knowledge of the phenomenology of accretion onto black holes has increased considerably. In particular, it has been possible to schematize the outburst evolution of transient systems on the basis of their spectral and timing properties, and link them to the ejection of relativistic jets as observed in the radio. Here, I present this scheme, concentrating on the properties of the quasi-periodic oscillations observed in the light curves and on the link with jet ejection. 相似文献
90.
Martin C. Weisskopf 《Advances in Space Research (includes Cospar's Information Bulletin, Space Research Today)》2006,38(12):2953-2958
The Chandra X-ray Observatory was launched on July 23, 1999. The first X-ray photons were detected on August 12 of that same year. Subsequently observations with the Observatory, which features sub-arcsecond angular resolution, have revolutionized our understanding of the X-ray emitting sky providing hosts of spectacular energy-resolved images and high-resolution spectra. Here we present a brief overview of Chandra X-ray Observatory observations of compact X-ray binaries. 相似文献