On the discrepancy between the magnetic D-component and the overhead horizontal current at high-latitudes     

L. Jalonen  T. Nygrén 《Planetary and Space Science》1979,27(7):1027-1032

The discrepancy between the overhead E-region current and the magnetic D-component is studied using data obtained by the Chatanika incoherent scatter radar (L = 5.6). The F-region horizontal current is estimated to be too small to cause the observed D-deflection. Also, the assumption that the magnetic effects of the Pedersen and field-aligned currents cancel each other on the ground is shown to be inadequate to solve the problem. The significance of the inclination angle in the data analysis and the importance of the field-aligned current sheets are discussed.  相似文献   

Earthquake prediction | Developments in Solid Earth Geophysics, 9. Tsuneji Rikitake. Elsevier,Amsterdam, 1976, xvi + 357 pp., Dfl.95.00     

P. Hédervári 《Engineering Geology》1977,11(2):149-151

  相似文献   

A relation in families of periodic solutions     

M. Hénon 《Celestial Mechanics and Dynamical Astronomy》1977,15(1):99-105

We show the existence of a general relation between the parameters of periodic solutions in dynamical systems with ignorable coordinates. In particular, for time-independent systems with an axis of symmetry, the relation takes the form T/A=–/E, whereT is the period,A is the angular momentum, is the angle through which the system has rotated after one period, andE is the energy.  相似文献   

The north-south distribution of major solar flare events,sunspot magnetic classes and sunspot areas (1955–1974)     

Roy  J. -René 《Solar physics》1977,52(1):53-61

The north-south incidence has been studied of 31 white-light flares observed since 1859 and of 1669 events meeting the criteria for major flares of Dodson and Hedeman (1971) for the period 1955–1974. The asymmetry in favor of the northern hemisphere increases strikingly with the importance of the events. Similarly, magnetically complex sunspot groups (Mt. Wilson classes, and) display a more pronounced asymmetry in favor of the north than non-complex groups for 1962–1970. Contrary to the flare asymmetry, the spottedness asymmetry is independent of the size of sunspots.  相似文献   

X-ray imaging of three flares during the impulsive phase     

André Duijveman  Peter Hoyng  Marcos E. Machado 《Solar physics》1982,81(1):137-157

The impulsive phases of three flares that occurred on April 10, May 21, and November 5, 1980 are discussed. Observations were obtained with the Hard X-ray Imaging Spectrometer (HXIS) and other instruments aboard SMM, and have been supplemented with Hα data and magnetograms. The flares show hard X-ray brightenings (16–30 keV) at widely separated locations that spatially coincide with bright Hα patches. The bulk of the soft X-ray emission (3.5–5.5 keV) originates from in between the hard X-ray brightenings. The latter are located at different sides of the neutral line and start to brighten simultaneously to within the time resolution of HXIS. Concluded is that:

1. The bright hard X-ray patches coincide with the footpoints of loops.
2. The hard X-ray emission from the footpoints is most likely thick target emission from fast electrons moving downward into the dense chromosphere.
3. The density of the loops along which the beam electrons propagate to the footpoints is restricted to a narrow range (10⁹ < n < 2 × 10¹⁰ cm^-3), determined by the instability threshold of the return current and the condition that the mean free path of the fast electrons should be larger than the length of the loop.
4. For the November 5 flare it seems likely that the acceleration source is located at the merging point of two loops near one of the footpoints.

It is found that the total flare energy is always larger than the total energy residing in the beam electrons. However, it is also estimated that at the time of the peak of the impulsive hard X-ray emission a large fraction (at least 20%) of the dissipated flare power has to go into electron acceleration. The explanation of such a high acceleration efficiency remains a major theoretical problem.  相似文献   

Spatial and temporal evolution of soft and hard X-ray emission in a solar flare     

Marcos E. Machado  André Duijveman  Brian R. Dennis 《Solar physics》1982,79(1):85-106

We study the spatial and temporal characteristics of the 3.5 to 30.0 keV emission in a solar flare on April 10, 1980. The data were obtained by the Hard X-ray Imaging Spectrometer aboard the Solar Maximum Mission Satellite. It is complemented in our analysis with data from other instruments on the same spacecraft, in particular that of the Hard X-ray Burst Spectrometer.Key results of our investigation are: (a) Continuous energy release is needed to substain the increase of the emission through the rising phase of the flare, before and after the impulsive phase in hard X-rays. The energy release is characterized by the production of hot (5 × 10⁷ T 1.5 × 10⁸ K) thermal regions within the flare loop structures. (b) The observational parameters characterizing the impulsive burst show that it is most likely associated with non-thermal processes (particle acceleration). (c) The continuous energy release is associated with strong chromospheric evaporation, as evidenced in the spectral line behavior determined from the Bent Crystal Spectrometer data. Both processes seem to stop just before flare maximum, and the subsequent evolution is most likely governed by the radiative cooling of the flare plasma.  相似文献   

Thermoluminescence of the lunar surface     

Marie-Lise Chanin  Véronique Lepine  Jacques E. Blamont 《Earth, Moon, and Planets》1982,27(2):143-163

Observations of the lunar luminescence are reported for a dozen of specific Moon features using the line-depth method with a high resolution spectroscopic technique. The data indicate a variation of the Moon proper emission as a function of the phase angle which is interpreted as a proof of the thermoluminescent origin of this emission.  相似文献   

Les gisements d'or des tonalites archéennes (Abitibi,Québec)     

M. Jébrak 《Mineralium Deposita》1992,27(1):1-9

Résumé De nombreux gisements ont été mis en exploitation depuis une dizaine d'années dans des plutons granitiques de la ceinture de roches vertes archéennes de l'Abitibi. La plupart d'entre eux sont encaissés par des faciès sodiques. Dans la zone sud-est de cette ceintúre, il existe deux types de concentrations, des zones filoniennes et des disséminations à caractère porphyrique.Les gisements filoniens sont encaissés dans des sills ou des dykes de tonalite-trondhjemite. Deux associations minéralogiques sont distinguées, l'une avec tourmaline et scheelite, l'autre avec hématite et métaux de base, spécifiques de chacun des blocs lithotectoniques qui composent la ceinture. Les variations paragénétiques peuvent être mise en relation avec la profondeur de mise en place des systèmes hydrothermaux. A l'échelle d'un bloc, on observe des variations de la structure des minéralisations controlées par les variations de la pression de fluide, plus importante au coeur des massifs et conduisant à des structures plus régulières empruntant des zones de faiblesse préexistantes.Les disséminations sont associées à un granite tardif issu de la refusion de tonalites. Dans la région de Launay, près d'Amos, l'or est associé à des zones d'épisyénites avec pyrite et molybdénite, ou avec des zones de cisaillement. Elles pourraient correspondre à des concentrations plus précoces.

---

Several deposits have been developped since 10 years in granitics plutons of the Archean greenstone belt of Abitibi. Most of them are hosted by Na-rich granitoids. In the south-eastern part of Abitibi, two main type of deposit may be distinguished:The lode type is hosted in pre-tectonic dykes or sills of tonalite-trondhjemite. Two mineralogical association are caracterised, one with tourmaline, scheelite, the other with hematite, and seems specific of lithotectonic blocs. Paragenetic variations may be related to vertical variations of deposition. On a bloc scale, high fluid pressure predominate in the center of pluton and may be responsible for more regular structure.The disseminated type is hosted in late granodioritic intrusions associated with tonalite. The only occurrence of that type is the Launay deposit, near Amos. Gold is associated either with abite-rich episyenite, with pyrite and Mo, or with shear-zone cross-cutting the granitic intrusions.

  相似文献   

Synchronous aperture synthesis observations of pulsars     

R. G. Strom  H. W. Van Someren Gréve 《Astrophysics and Space Science》1990,171(1-2):351-355

By modifying the online software of the Westerbork Synthesis Radio Telescope it is possible to sample the radio emission from a field containing a pulsar synchronously with the pulsed signal. Recording the emission from eight separate temporal windows, we can simultaneously observe both the on-pulse and off-pulse signals. We are using this technique for three different kinds of pulsar investigation: (a) to check and improve the positions of some pulsars; (b) to look for unpulsed components; and (c) to search for weak extended emission around pulsars. Observations have been carried out at 6, 21, 49, and 92 cm. Examples of results from all three types of investigation are given.Paper presented at the 11th European Regional Astronomical Meetings of the IAU on New Windows to the Universe, held 3–8 July, 1989, Tenerife, Canary Islands, Spain.  相似文献   

Photometry of AR Lac     

M. J. Arévalo  C. Lázaro 《Astrophysics and Space Science》1990,169(1-2):255-256

Visible photometry of the RS CVn system AR Lac is presented. We find some interesting features in the light curves. Also a possible oscillation with period 1.05 hr arises from the data. A new determination of the geometrical parameters of the system is given.Paper presented at the 11th European Regional Astronomical Meetings of the IAU on New Windows to the Universe, held 3–8 July, 1989, Tenerife, Canary Islands, Spain.  相似文献