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1.
We study the effects of the sector structure of the interplanetary magnetic field (IMF) on the Galactic cosmic ray (GCR) anisotropy at solar minimum by using Global Network neutron monitor data. The hourly neutron monitor data for 1976 were averaged for the positive (+) and negative (–) IMF sectors (+ and – correspond to the antisolar and solar directions of magnetic field lines, respectively) and then processed by the global survey method. We found that the magnitude of the GCR anisotropy vector is larger in the positive IMF sector and that the phase shifts toward early hours. The derived GCR components A r, A , and A for the different + and – sectors are then used to calculate the angle ( 46°) between the IMF lines and the Sun–Earth line, the solar wind velocity U ( 420 km/s), the ratio of the perpendicular (K ) and parallel (K ||) diffusion coefficients K /K || = ( 0.33), and other parameters that characterize the GCR modulation in interplanetary space.  相似文献   

2.
On the assumption that solar flares are due to instabilities which occur in current sheets in the Sun's atmosphere, one may classify magnetic-field configurations associated with flares into two types. One is characterized by closed current sheets, magnetic-field lines adjacent to these sheets beginning and ending at the Sun's surface. The other is characterized by open current sheets, magnetic-field lines adjacent to these sheets beginning at the Sun's surface but extending out into interplanetary space. Flares associated with open current sheets can produce Type III radio bursts and high-energy-particle events, but flares associated with closed current sheets cannot. The flare of July 6, 1966 apparently consisted of one flare of each type.  相似文献   

3.
H observations, using the Multichannel Subtractive Double Pass (MSDP) spectrograph operating on the Meudon Solar Tower, have been made of an active region filament which undergoes a disparition brusque. The period of observation was from 10 45 to 13 30 UT on 22 June, 1981. Velocity and intensity fluctuations in H were measured. The proper motions of ejecta were followed allowing their trajectories and vector velocities to be determined. To model the dynamics of ejecta several models using thermal or magnetic driving forces are compared. The most promising model explains the motion as the consequence of magnetic stresses acting on an isolated magnetized plasmoïd in a diverging flux tube.  相似文献   

4.
It is suggested that boundary conditions for solar wind/lunar limb interactions are active. The whole-Moon limb does not evoke a shock cone because warm (13 eV/electron) solar wind electrons are replaced by cool (2 eV/electron) photoelectrons that are ejected from the generally smooth areas of the lunar terminator illuminated at glazing angles by the Sun. A localized volume of low thermal pressure is created in the solar wind by these cool photoelectrons. The solar wind expands into this turbulence-suppressive volume without shock production. Conversely, directly illuminated highland areas exchange hot photoelectrons (> 20 eV/electron) for warm solar wind electrons. The hot electrons generate a localized pressure increase (p) in the adjacent solar wind flow which evokes a shock streamer in the solar wind. Shock streamers are identifiable by a coincident increase in the magnitude (B p) of the solar wind magnetic field immediately external to the lunar wake. Shock occurrence is controlled by lunar topography, solar activity in the hard ultraviolet (> 20 eV), solar wind electron density and thermal velocity, and the intensity of the solar wind magnetic field.Paper dedicated to Professor Harold C. Urey on the occasion of his 80th birthday on 29 April 1973.The Lunar Science Institute is operated by the Universities Space Research Association under Contract No. NSR 09-051-001 with the National Aeronautics and Space Administration.  相似文献   

5.
We report on a new ESB source, as defined by Allenet al. (1991), with Wolf-Rayet (WR) bands in its optical spectrum. The WR bump at 4605-4686 is detected. The bump consists of broad HeII 4686, NV4605-4619, NIII4634-41, and possibly, CIII4647-52 emission. The narrow nebular lines are clearly discernable on our spectrum. The number of WR stars derived from the luminosity of HeII4686 is about 8100. The oxygen abundance is about 9.06×10–4, greater than the solar value.  相似文献   

6.
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The structure of rotating magnetic polytropes is considered in Roche approximation. Investigation of the influence of poloidal as well as toroidal magnetic fields on the conditions of the beginning of matter outflow due to rotational instability is carried out. The influence of the turbulent convection and twisting of magnetic force-lines on the time of smoothing of differential rotation is considered. The estimate of the magneto-turbulence energy generated by differential rotation is presented. Both maximum possible energy output and duration of the quasi-statical evolution phase up to the appearance of hydrodynamic instability due to the effects of general relativity are calculated for supermassive magnetic polytropes of index three with uniform or differential rotation. The radius-mass relation is obtained for supermassive differentially-rotating magnetic polytropes referring to the longest part of the quasi-statistical evolution stage; some consequences are pointed out, including the period-luminosity relation.The evolution of the considered models of supermassive rotating magnetic polytropes with different character of rotation and different geometry of a magnetic field is discussed.The results obtained are summarized in the last section.

English translation will appear in the next issue ofAstrophys. Space Sci.

Receipt delayed by postal strike in Great Britain  相似文献   

7.
I have studied the observational relationship between the location of flare sites in active regions and three other observables, viz., H line width, hard X-ray burst parameters, and peak microwave fluxes. Results suggest that the strength of the magnetic field plays a role in governing the magnitudes of these emissions. Qualitative relationships are derived on the assumption of proportionality between the spectral maximum frequency of the associated microwave burst and the field strength in the microwave source.The relationship inferred between the power in thick target electrons (derived from the hard X-ray burst) and the column density of second-level hydrogen atoms (derived from the H line widths) is compared with calculations by Brown (1973) and Canfield (1974).The line widths observed for two white light flares suggest that a criterion for detectable continuum emission in disk flares is an H line width 20 Å.Operated by the Association of Universities for Research in Astronomy, Inc., under contract with the National Science Foundation.  相似文献   

8.
Ravindra  B.  Venkatakrishnan  P. 《Solar physics》2003,214(2):267-285
Near simultaneous coronal EUV images were used to show that the He ii 304 network brightening is independent of coronal EUV radiation. We studied the quantitative relation between the intensity of He ii 304 network brightening with the associated magnetic elements. An almost linear relationship was found between the He ii 304 network brightening and the magnetic field for a field strength higher than 10 G with exceptions at neutral lines and in the intra-network. We also calculated the most probable formation height of He ii 304 network elements using the potential extrapolation of the photospheric magnetic field. The results show that He ii 304 network elements form at or around 3000 km above the height of the layer at which the sources of magnetic flux are deployed.  相似文献   

9.
Analytic and numerical results are presented for the growth rate of Langmuir waves due to a loss-cone distribution of energetic electrons. The effect of the magnetic field on the wave-particle interaction is ignored, and the resonance condition is described in terms of a resonance hyperboloid in momentum space. The collisional evolution of a distribution of magnetically trapped electrons is followed numerically to show how a gap distribution develops. The growth is most favorable for an intermediate sized loss cone ( 45 °) and a gap distribution in which the mean energy of the suprathermal electrons is much larger than the thermal energy of the background electrons. It is plausible that loss-cone gap distributions do develop in the solar corona, and that they should lead to second harmonic plasma emission weakly polarized in the x-mode.  相似文献   

10.
A new sufficiently compact code LINESPEC is described which is designed to determine the kinetic (collisional+photo) ionization equilibrium in a slab of a hot (T104K) rarefied gas, and to simulate synthetic absorption-line spectra formed due to passing continuous radiation (from a quasar) through the slab. Eighty-six resonant absorption lines of ions and atoms of H, He, C, N, O, Ne, Mg, Al, Si, S, Ca, Fe are included with wavelengths in the range 9125000 Å. the behaviour and observability of various lines are analysed as a function of intensity of the ionizing radiation and kinetic plasma temperature (for a power-law spectrum of ionizing photons,N ph (E) E – with =1.5;E is photon energy). For the purely collisional ionization (N ph =0), the spectrum contains various combinations of absorption lines of hydrogen and/or of atoms and ions of other elements, the relative intensities of the lines being strongly temperaturedependent. If the ionizing radiation is intense enough, the L line dominates. In a wide parameter range L may be the only line visible in the UV spectral range.  相似文献   

11.
A model of interplanetary and coronal magnetic fields   总被引：5，自引：0，他引：5  
A model of the large-scale magnetic field structure above the photosphere uses a Green's function solution to Maxwell's equations. Sources for the magnetic field are related to the observed photospheric field and to the field computed at a source surface about 0.6 R above the photosphere. The large-scale interplanetary magnetic field sector pattern is related to the field pattern at this source surface. The model generates magnetic field patterns on the source surface that compare well with interplanetary observations. Comparisons are shown with observations of the interplanetary magnetic field obtained by the IMP-3 satellite.  相似文献   

12.
We study a theory for the ninth satellite of Saturn, Phoebe, based on the literal solution we have obtained in the main problem of the lunar theory.These series were computed by solving, by successive approximations, the Lagrange's equations expressed in variables, functions of the elliptic elements.We may consider the case of Phoebe simpler than a lunar case because we seek less precision (1/10 geocentric) than in the Lunar case, although the eccentricity of Phoebe is stronger.Main problem: our series are computed to the complete seventh order and a great part of the perturbations of the eighth and ninth order, where we have attributed to the small lunar parameters the order 1 tom 0=n/n 0,e 0,e, sin (i 0/2), the order 2 to 0=(a 0/a)((M 1–)/(M 1+M)) and the order 4 toµ 0(a 0/a)M 1 M/M 1 2 –M 2.In the case of Phoebe,µ 0 equal zero and ±0 is the ratioa 0/a.We study the further development of these series by using, instead of parameterm 0, the quantity m 0=n/n 0–m 1 wherem 1 is an approached value ofm 0, in order to accelerate the convergence of the series with respect tom 0.Comparison with a numerical integration we are adjusting a numerical integration to the observations. We have already more than 100 observations, for the period 1900–1957.At first, we compare the series of the main problem to a numerical integration of the Keplerian problem.

Proceedings of the Conference on Analytical Methods and Ephemerides: Theory and Observations of the Moon and Planets. Facultés universitaires Notre Dame de la Paix. Namur, Belgium, 28–31 July, 1980.  相似文献   

13.
The correlation of the mean solar magnetic field and the interplanetary magnetic field reported by Wilcox et al. (1969) and Severny et al. (1970) has been interpreted by comparing the relationship of the measurement of the mean solar field with the physics involved in the formation of the interplanetary field. The high correlation observed is thus interpreted as a fortuitous correspondance between two integrals. The high correlation thus provides further support for the source surface model involved in these calculations. A new method is then suggested for observing the mean solar field that might improve the correlations slightly.  相似文献   

14.
The HXIS, a joint instrument of the Space Research Laboratory at Utrecht, The Netherlands, and the Department of Space Research of the University of Birmingham, U.K., images the Sun in hard X-rays: Six energy bands in energy range 3.5–30 keV, spatial resolution 8 over Ø 240 and 32 over Ø 624 field of view, and time resolution of 0.5–7 s depending on the mode of operation. By means of a flare flag it alerts all the other SMM instruments when a flare sets in and informs them about the location of the X-ray emission. The experiment should yield information about the position, extension and spectrum of the hard X-ray bursts in flares, their relation to the magnetic field structure and to the quasi-thermal soft X-rays, and about the characteristics and development of type IV electron clouds above flare regions.  相似文献   

15.
Low-frequency gravitational radiation, with wavelengths reaching or exceeding interplanetary distances, and with a mean energy density of the order of the critical cosmological density c , generates a frequency-shift of order/10–15 h 0(1/108km)(/ c )1/2 in electromagnetic signals transponded by interplanetary spacecraft at a distancel from the Earth.  相似文献   

16.
The profiles of the emission lines of H HeI 5876 and HeII 5411 in the spectrum of AG Peg obtained in the minimum of 1985 are described. The light curves in UBVRI system are presented. No indication for the presence of a magnetic field exceeding the error of observations (200 gauss) has been found.Paper presented at the IAU Colloquium No. 93 on Cataclysmic Variables. Recent Multi-Frequency Observations and Theoretical Developments, held at Dr. Remeis-Sternwarte Bamberg, F.R.G., 16–19 June, 1986.  相似文献   

17.
A flare event occurred which involved the disappearance of a filament near central meridian on 29 August 1973. The event was well observed in X-rays with the AS & E telescope on Skylab and in H at BBSO. It was a four-ribbon flare involving both new and old magnetic inversion lines which were roughly parallel. The H, X-ray, and magnetic field data are used to deduce the magnetic polarities of the H brightenings at the footpoints of the brightest X-ray loops. These magnetic structures and the preflare history of the region are then used to argue that the event involved a reconnection of magnetic field lines rather than a brightening in place of pre-existing loops. The simultaneity of the H brightening onsets in the four ribbons and the apparent lack of an eruption of the filament are consistent with this interpretation. These observations are compared to other studies of filament disappearances. The preflare structures and the alignment of the early X-ray flare loops with the H filament are consistent with the schematic picture of a filament presented first by Canfield et al. (1974).  相似文献   

18.
We introduce a method for constructing large-scale (0.25 AU) interplanetary magnetic field lines using only solar wind velocity from well-separated appropriately located spacecraft. The technique is based on labeling the field lines at each spacecraft with their coronal connection longitudes calculated in the EQRH (extrapolated quasi-radial hypervelocity) approximation (Nolte and Roelof, 1973). Even though the EQRH approximation is most applicable to quasi-steady solar wind, we propose that it should also be satisfactorily accurate for moderately evolving conditions. For strongly evolving conditions (e.g., flare-associated plasma) we propose a straightforward correction based on the inferred coronal longitudinal velocity profile. To illustrate the multispacecraft EQRH technique, we perform a calculation in which the interplanetary field lines in a model evolving solar wind disturbance are deduced from model observations at separated spacecraft. Since the expected agreement is found, we use data from Pioneers 8 and 9 and Vela to construct field lines for an unusually quiet period (April 26–30, 1969) and for a flare-associated disturbance accompanied by a Forbush decrease (March 23–25, 1969). The deduced field lines (even though strongly distorted by the disturbance), order the onsets of the Forbush decrease at the separated spacecraft, and the interplanetary plasma and field structures correspond to equatorial structures apparent in H synoptic charts of chromospheric magnetic features.  相似文献   

19.
McClymont  A. N.  Jiao  L.  MikiĆ  Z. 《Solar physics》1997,174(1-2):191-218
An overview of the whole process of reconstructing the coronal magnetic field from boundary data measured at the photosphere is presented. We discuss the errors and uncertainties in the data and in the data reduction process. The problems include noise in the magnetograph measurements, uncertainties in the interpretation of polarization signals, the 180° ambiguity in the transverse field, and the fact that the photosphere is not force-free. Methods for computing the three-dimensional structure of coronal active region magnetic fields, under the force-free assumption, from these boundary data, are then discussed. The methods fall into three classes: the extrapolation technique, which seeks to integrate upwards from the photosphere using only local values at the boundary; the current-field iteration technique, which propagates currents measured at the boundary along field lines, then iteratively recomputes the magnetic field due to this current distribution; and the evolutionary technique, which simulates the evolution of the coronal field, under quasi-physical resistive magnetohydrodynamic equations, as currents injected at the boundary are driven towards the observed values. The extrapolation method is mathematically ill-posed, and must be heavily smoothed to avoid exponential divergence. It may be useful for tracing low-lying field lines, but appears incapable of reconstructing the magnetic field higher in the corona. The original formulation of the current-field iteration method had problems achieving convergence, but a recent reformulation appears promising. Evolutionary methods have been applied to several real datasets, with apparent success.  相似文献   

20.
The plot of the X-ray luminosity (in 0.5–4.5 KeV band and for Friedmann universe withq 0=+1) of the brightest X-ray QSO at each redshift against redshift shows that the X-ray luminosity increases more or less monotonically with redshift uptoz3. This result has been attributed to the selection effect known as the volume effect. When this selection effect is taken into account in the optical, radio and X-ray windows of the electromagnetic spectrum, a sample of the brightest X-ray QSO's is obtained which shows a small dispersion in X-ray luminosity: logL 1=46.15±0.25. The redshift-X-ray flux density plot for this sample gives slopes of both regression lines which agree, at a confidence level of 95% or greater, with the slopes expected theoretically if the redshifts of the QSO's are cosmological in nature.  相似文献   

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