Extensive observations of solar flares made in high energy bands during the maximum of the present solar cycle are discussed with a special reference to the results from HINOTORI, and with attention to the relevant flare models. The hard X-ray (HXR) images from HINOTORI showed mostly coronal emission at 20–25 keV suggesting that the HXR is emitted from multiple coronal loops, consistent with the non-thermal electron beam model in a high density corona. The thermal HXR model seems to be inconsistent with some observations. Three types of flares which have been classified from the Hinotori results are described, along with newly discovered hot thermal component of 30–40 million K which contributes thermal HXR emission. A summary is given for the characteristics of the energy release in an impulsive burst; and an empirical model is described, which explains simultaneous energy releases in multiple loops and successive movements of the release site as suggested from the HXR morphology. The discovery of large blue-shifted hot plasma from the soft X-ray line spectrum leads to some quantitative arguments for the evaporating flare model. An electron-heated flare atmosphere appears to explain various observations consistently.Invited paper presented at the IAU Third Asian-Pacific Regional Meeting, held in Kyoto, Japan, between 30 September–6 October, 1984. 相似文献
We present the set-up and the results of a supercritical radiative shock experiment performed with the LULI nanosecond laser
facility. Using specific designed targets filled with xenon gaz at low pressure, the propagation of a strong shock with a
radiative precursor is evidenced. The main measured quantities related to the shock (electronic density, propagation velocities,
temperature, radial dimension) are presented and compared with various numerical simulations. 相似文献
The dependence of coupling constants in a coupled oscillator model is examined with simplified methods. The Lyapunov exponents are preliminary introduced for the model. The behaviors of oscillator model are examined in a parameter plane. So-called the Arnold's tongues for phase-locking states are observed in fractal patterns. 相似文献
The Nidar ophiolite complex is exposed within the Indus suture zone in eastern Ladakh, India. The suture zone is considered to represent remnant Neo-Tethyan Ocean that closed via subduction as the Indian plate moved northward with respect to the Asian plate. The two plates ultimately collided during the Middle Eocene. The Nidar ophiolite complex comprises a sequence of ultra-mafic rocks at the base, gabbroic rocks in the middle and volcano-sedimentary assemblage on the top. Earlier studies considered the Nidar ophiolite complex to represent an oceanic floor sequence based on lithological assemblage. However, present study, based on new mineral and whole rock geochemical and isotopic data (on bulk rocks and mineral separates) indicate their generation and emplacement in an intra-oceanic subduction environment. The plutonic and volcanic rocks have nearly flat to slightly depleted rare earth element (REE) patterns. The gabbroic rocks, in particular, show strong positive Sr and Eu anomalies in their REE and spidergram patterns, probably indicating plagioclase accumulation. Depletion in high field strength elements (HFSE) in the spidergram patterns may be related to stabilization of phases retaining the HFSE in the subducting slab and / or fractional crystallization of titano-magnetite phases. The high radiogenic Nd- and low radiogenic Sr-isotopic ratios for these rocks exclude any influence of continental material in their genesis, implying an intra-oceanic environment.
Nine point mineral–whole rock Sm–Nd isochron corresponds to an age of 140 ± 32 Ma with an initial 143Nd/144Nd of 0.513835 ± 0.000053 (ENdt = + 7.4). This age is consistent with the precise Early Cretaceous age of Hauterivian (132 ± 2 to 127 ± 1.6 Ma) to Aptian (121 ± 1.4 to 112 ±1.1 Ma) for the overlying volcano-sedimentary (radiolarian bearing chert) sequences based on well-preserved radiolarian fossils (Kojima, S., Ahmad, T., Tanaka, T., Bagati, T.N., Mishra, M., Kumar, R. Islam, R., Khanna, P.P., 2001. Early Cretaceous radiolarians from the Indus suture zone, Ladakh, northern India. In: News of Osaka Micropaleontologists (NOM), Spec. Vol., 12, 257–270.) and cooling ages of 110–130 Ma based on 39Ar/40Ar for Nidar–Spontang ophiolitic rocks (Mahéo, G., Berttrand, H., Guillot, S., Villa, I. M., Keller, F., Capiez, P., 2004. The South Ladakh Ophiolites (NW Himalaya, India): an intra-oceanic tholeiitic arc origin with implications for the closure of the Neo-Tethys. Chem. Geol., 203, 273–303.). As these gabbroic and volcanic rocks are interpreted to be arc related, the new Sm–Nd age data may indicate that intra-ocean subduction in the Neo-Tethyan ocean may have started much before 140 ± 32 Ma as this date is interpreted as the age of crystallization of the arc magma. Present and published age data on the arc magmatic rocks from the Indus suture zone may collectively indicate episodic magmatism with increasing maturity of the arc from more basic (during ~ 140 ± 32 Ma) when the arc was immature through intermediate (andesitic/granodioritic) at ~ 100 Ma to more felsic (rhyolitic/dioritic) magmatism at ~ 50–45 Ma, when the Indian and the Asian plates collided. 相似文献
A brief review was made of storm runoff processes and the mechanisms of its generation in relation to subsurface water behaviors in a small forested drainage basin located in the western suburbs of Tokyo, Japan. The results of field investigations showed that the main source of storm runoff was groundwater flow and that the rapid and large amounts of groundwater discharge during a storm event could not be explained solely by the traditional concept of Darcian matrix flow. Several mechanisms such as pipe flow, air pressure effect, and capillary barrier effect were recognized that would induce a rapid response of groundwater to storm events depending on differences in local hydrologic conditions. All of these mechanisms were chiefly attributed to inhomogeneities of the soil deposits. The importance of dynamic behaviors of subsurface water during a storm event was emphasized in considering the mechanism of storm runoff generation. 相似文献
Fine particles of various chemical substances—carbon, iron, iron oxide and silica—which are expected to exist in interstellar space are prepared in argon gas. The size, shape, and crystal structure of the powder particles are studied by electron microscopy and electron diffraction, and may have some bearing on models of comets and of the solar nebula.The largest size we have obtained is about 0.1 μm and the smallest about 40Å. Generally the size becomes smaller for lower temperature and also for lower pressure. This tendency is discussed in connection with nucleation theories. Except for iron and iron oxide the powder particles have no crystal structure. 相似文献
Three dimensional electric fields were measured at the altitude of about 27 km in the stratosphere over the Pacific Ocean about 200–400 km away from the Sanriku coast of Honsyu Island (L = 1·4) on 16–17 October 1973, which was magnetically disturbed. The average horizontal electric field thus measured is about 10 mV/m, and the electric field vectors made clockwise semidiurnal rotations rather than diurnal. Daily variation of this electric field was compared with data at L = 2·7–3·5 published by Mozer (1973) and was found to be very similar. This suggests that these electric fields are of common origin in the plasmasphere. From their mean daily variation it is estimated that the plasmaspheric convection is decreased in the night side and is increased in the day side by 200–300 m/sec, and there is an outward flow in the first half of the afternoon and an inward flow in the plasma bulge region of about 500 m/sec. 相似文献
Rare-earth elements in a whole-rock sample and in major components of the Allende meteorite were investigated; for a few samples, abundances of Ba, Sr, Ca, and Al were also determined. Of the materials investigated in the present work, CaAl-rich inclusions G and O seem to be of the greatest significance. In spite of the minor difference in mineralogy between them, the apparent chondrite-normalized RE pattern is much different between these two inclusions. (Yb and Eu in inclusion G appear exceptionally irregular). This observation is inferred to reflect a rather subtle difference in condition of condensation. It is also worthwhile to note that, while two portions (pink and white) of the inclusion G show similar aspects in the abundances of lithophile trace elements investigated, they show a remarkable difference at the same time. The white portion (Gw) of inclusion G can be considered to be a mixture of chondritic material and highly fractionated material like the faintly pink portion (Gp) picked from the same inclusion. This would suggest the possibility that the Gp-like material was produced from chondritic dust.The “matrix” separated from Allende was found to be fractionated with respect to the RE abundances relative to representative chondrite. It has also a very high value for the Ba abundance. 相似文献