共查询到20条相似文献，搜索用时 140 毫秒
1.
We study the modulation of galactic cosmic rays (GCR) due to high-speed streams (HSS) identified in the solar wind. We compare the GCR modulation due to i) streams with different speed, ii) streams of different duration, and iii) streams from different solar sources. We apply the method of superposed-epoch analysis to analyze the interplanetary plasma and field parameters during the passage of streams with distinct plasma and field characteristics. We use the plasma/field characteristics to distinguish various features of solar sources and interplanetary structures, and discuss the observed differences in the cosmic-ray response. We study the influence of speed, duration, and solar sources of the streams on the GCR modulation. We discuss the relative importance of different solar-wind parameters in the modulation process. 相似文献
2.
Hirokazu Yoshimura 《Solar physics》1977,54(1):229-258
The simultaneous enhancement or subsidence of both the high-speed solar wind streams and the galactic cosmic rays in the minimum or the maximum phase of the solar cycle are interpreted in a unified manner by the concept of geometrical evolution of the general magnetic field of the corona-heliomagnetosphere system. The coronal general magnetic field evolves from an open dipole-like configuration in the minimum phase to a closed configuration with many loop-like formations in the maximum phase of the solar cycle. This concept, developed in a theoretical solar-cycle model driven by the dynamo action of the global convection, is examined and found to be valid by studying the evolution of the coronal general magnetic field calculated from the observed surface general magnetic field of 1959–1974. It is also found that the energy density of the poloidal component of the general surface field, from which the coronal field originates, attained a maximum in the maximum phase and showed a evolution with virtually no phase delay with respect to that of the toroidal component of the field, to which the sunspot activity is related. The subsidence of the high-speed solar wind in the maximum phase is understood as a braking of the solar wind streams by the tightly closed and strong coronal field lines in the lower corona in the maximum phase. The field lines of the heliomagnetosphere, which originate from the coronal field lines drawn by the solar wind, are inferred to be also more tightly closed at the heliopause in the maximum phase than in the minimum phase. The decrease of the galactic cosmic rays in the maximum phase (known as the Forbush's negative correlation between the galactic cosmic ray intensity and the solar activity or the Forbush solar-cycle modulation of the galactic cosmic rays) is interpreted as a braking of the cosmic rays by the closed magnetic field lines at the heliopause. The observed phase lag (approximately one year) of the galactic cosmic ray modulation with respect to the evolution of the solar cycle, and the observed absence of the gradient of the total cosmic ray intensity between 1 AU and 8 AU, are discussed to support this view of the cosmic ray modulation at the remote heliopause, and reject other hypotheses to explain the phenomenon in terms of the magnetic irregularities of various kinds carried by the solar wind: The short-term Forbush decrease at a time of a flare shows that the magnetic irregularities can react on the cosmic rays relatively near the Sun if they even played a dominant role in the long-term modulation. The concept of the general magnetic field of the corona and the surface is also used to understand the basic nature of the surface field itself, by comparing the geometry of the calculated coronal field lines with the eclipse photographs of the corona, and by discussing, in the context of the coronal general magnetic field associated with the solar cycle, the process of the emergence of the coronal field lines from the interior and the formation of the transequatorial arches and loops connecting the two hemispheres in the corona. 相似文献
3.
The dynamics of energetic radiation, i.e., particles of radiation belts and galactic and solar cosmic rays in Earth’s environment during solar and geomagnetic disturbances, is analyzed in a review based on the CORONAS-F experimental data. 相似文献
4.
The dissimilarity of the results of solar and galactic proton flux measurements made on different spacecraft is pointed out. It is caused, in addition to instrument errors, by differences in the temporal and spatial conditions of the measurements. We suggest using statistical analysis of proton fluences calculated for different long time intervals, from half a year to 10 years, for the optimization of the interplanetary proton database. An example of such analysis is presented and a probabilistic model of total proton fluences at the Earth’s orbit outside the magnetosphere, constructed using the analysis, is described. A formalized method for separating proton fluxes in solar proton events from protons of galactic cosmic rays is suggested. A conclusion is made that sources of cosmic ray protons with energies of less than 4 MeV should be examined in more detail. 相似文献
5.
We have correlated intensity decreases in the galactic component of cosmic rays observed at the Earth with solar phenomena. We have found that there exist intensity decreases detected underground, which are probably associated with long-lived interplanetary streams and which are not directly associated with single flares. We expect to detect the streams with underground monitors before the arrival of the streams at the Earth. The early detection will be in the northern or in the southern hemisphere, depending on the sign of the interplanetary field. 相似文献
6.
Kunitomo Sakurai 《Astrophysics and Space Science》1974,28(2):375-519
This paper discusses solar cosmic ray phenomena and related topics from the solar physical point of view. Basic physics of the solar atmosphere and solar flare phenomena are, therefore, considered in some detail. Since solar cosmic rays are usually produced by solar flares, we must first understand the processes and mechanism of solar flares, especially the so-called proton flares, in order to understand the acceleration mechanism of solar cosmic rays and their behaviour in both the solar atmosphere and interplanetary space. For this reason, detailed discussion is given on various phenomena associated with solar flares, proton flare characteristics, and the mechanism of solar flares.Since the discovery of solar cosmic rays by Forbush, the interplanetary space has been thought of as medium in which solar cosmic rays propagate. In this paper, the propagation of solar cosmic rays in this space is, therefore, discussed briefly by referring to the observed magnetic properties of this space. Finally, some problems related to the physics of galactic cosmic rays are discussed.Astrophysics and Space Science Review Paper. 相似文献
7.
Zhou Da-zhuang
K. K. Tang
《Chinese Astronomy and Astrophysics》1991,15(4):416-422We calculate the spectrum of the diffuse cosmic gamma ray in the single and double leaky box models for several galactic distribution laws of cosmic rays and hdydrogen. The results show that LI Ti-pei's distribution law for the cosmic rays is the best and that the number of interstellar hydrogen molecules should be less than Gordon's value divided by 1.7. The observed spectrum of gamma rays can be reproduced by a suitable choice of the galactic distributions within certain ranges. 相似文献
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9.
With the help of empirical data concerning the latitudinal distribution of galactic gamma rays the contribution of inverse Compton scattered gamma rays is calculated using various models concerning the distribution of high energy cosmic ray electrons perpendicular to the galactic plane. It is shown that gamma ray astronomy from regions with vanishing stellar and interstellar matter densities at energies greater than 100 MeV provides instructive information on the cosmic ray electron density. We find evidence for the existence of a broad galactic electron disk with a total thickness of at least 6.4 kpc. The uncertainties of the cosmic ray electron spectrum measurements above 100 GeV imply an additional uncertainty in the inverse Compton source function of at least a factor 6. 相似文献
10.
The modulation of galactic cosmic rays, as derived from ground-based neutron monitors over a solar cycle appears to be a good indicator of solar activity. Especially good correlation was found between short-term variations of cosmic ray flux and solar UV emission in the region of 250 nm during one year (1982). 相似文献
11.
The case is made for most cosmic rays having come from galactic sources. ‘Structure’, i.e. a lack of smoothness in the energy spectrum, is apparent, strengthening the view that most cosmic rays come from discrete sources, supernova remnants being most likely. 相似文献
12.
We discuss the present status of our understanding of the transport and acceleration of anomalous cosmic rays and the transport
of galactic and CIR-accelerated particles in the heliosphere. Currently, two- and three-dimensional numerical codes can accurately
model many of the observed phenomena – with the major current uncertainties being the values of the parameters such as the
diffusion coefficients and the effects of the poorly understood structure beyond the termination shock. We illustrate the
nature of the phenomena by discussing in detail the response of energetic particles to co-rotating interaction regions, the
acceleration of singly- and multiply-charged anomalous cosmic rays, and the effects of galactic cosmic rays on the structure
of the solar wind and its termination shock.
This revised version was published online in July 2006 with corrections to the Cover Date. 相似文献
13.
Cosmic rays are a sample of solar, galactic and extragalactic matter. Their origin and properties are one of the most intriguing question in modern astrophysics. The most energetic events and active objects in the Universe: supernovae explosion, pulsars, relativistic jets, active galactic nuclei, have been proposed as sources of cosmic rays although unambiguous evidences have still to be found. Electrons, while comprising ∼1% of the cosmic radiation, have unique features providing important information regarding the origin and propagation of cosmic rays in the Galaxy that is not accessible from the study of the cosmic-ray nuclear components due to their differing energy-loss processes. In this paper we will analyse, discussing the experimental uncertainties and challenges, the most recent measurements on cosmic-ray nuclei and, in particular, electrons with energies from tens of GeV into the TeV region. 相似文献
14.
15.
There are two types of high-speed solar wind streams classified in two categories:coronal-hole and solar-flare-generated streams. These two types are classified in two categories considering the bulk speed, proton density, temperature and magnetic field in the interplanetary medium. Their effects on cosmic ray intensity have been studied on a short-term basis during 1980–1986. Daily means of one middle and one low-latitude set of neutron monitor data have been taken for analysis using the Chree method of superposed epochs. The investigation indicates that the solar-flare-generated high-speed solar wind streams are more effective in producing cosmic ray decreases than are the coronal-hole generated streams. 相似文献
16.
In the present study the occurrence of an unusual class of low amplitude anisotropic wave trains in the cosmic ray neutron intensity, which is distinctly different from the average diurnal variation as well as from other recognized types of low amplitude anisotropic wave trains are noted and the directional distribution in the interplanetary space determined. The major objective of this paper is to study the first three harmonics of low amplitude anisotropic wave trains of cosmic ray intensity over the period 1981–1994 for Deep River neutron monitoring station. The significant characteristic of these events is that the low amplitude wave trains shows a maximum intensity of diurnal component in a direction earlier than 18:00 h/co-rotational direction. It is noticed that these events are not caused either by the high-speed solar wind streams or by the sources on the Sun responsible for producing these streams such as polar coronal holes. However the possibility of occurrence of these events during high-speed solar wind streams cannot be denied. The occurrence of low amplitude events is dominant for positive polarity of Bz. The disturbance storm time index i.e. Dst, remains consistently negative only for majority of the low amplitude wave train events, which is never been reported earlier. The amplitude as well as direction of first two harmonics seems to remain unaffected with the variation in the Dst and Ap-index. However, the amplitude as well as direction of third harmonic found to deviates with the increase of Dst and Ap-index. The corotating streams produce significant deviations in cosmic ray intensity as well as in solar wind speed during low amplitude anisotropic wave train events. 相似文献
17.
Cosmic rays are ubiquitous in space, and the essential similarity of their energy spectra in many different regions places significant general constraints on the mechanisms for their acceleration and confinement. Diffusive shock acceleration is at present the most successful acceleration mechanism proposed, and, together with transport in Kolmogorov turbulence, can account for the universal specta. A unique laboratory for studying the acceleration and transport of charged particles is the outer heliosphere, including the solar wind termination shock and heliosheath.
A widely accepted paradigm for the transport and acceleration of energetic particles in the heliosphere has evolved over the last few decades. This picture has successfully explained many features of the modulation of galactic cosmic rays and the transport and acceleration of anomalous cosmic rays at the solar-wind termination shock. Recent Voyager observations near and beyond the termination shock have revealed new, and in some cases, unexpected phenomena which have led to questions concerning the established paradigm. The physical interpretation of the observations requires a blunt termination shock, rapid inward motion of the shock and temporal variations over time scales ranging from hours to 22 years. Incorporation of these into the physics has promise of explaining most, if not, all of the observed phenomena while retaining the advantages of the termination shock paradigm for both galactic and anomalous cosmic rays. 相似文献
18.
Astrophysics - We study the modulation of galactic cosmic rays due to magnetic clouds observed during solar cycles 23 and 24 (1996-2018). We utilize solar wind plasma and field data together with... 相似文献
19.
We investigate the problem of transition from galactic cosmic rays to extragalactic ultra-high energy cosmic rays. Using the model for extragalactic ultra-high energy cosmic rays and observed all-particle cosmic ray spectrum, we calculate the galactic spectrum of iron nuclei in the energy range 108–109 GeV. The flux and spectrum predicted at lower energies agree well with the KASCADE data. The transition from galactic to extragalactic cosmic rays is distinctly seen in spectra of protons and iron nuclei, when they are measured separately. The shape of the predicted iron spectrum agrees with the Hall diffusion. 相似文献
20.
Yu. I. Fedorov B. A. Shakhov Yu. L. Kolesnyk 《Kinematics and Physics of Celestial Bodies》2017,33(1):1-12
The process of heliospheric modulation of intensity of galactic cosmic rays is investigated by solving the transport equation. The spatial-energetic distribution of cosmic rays in the present epoch and in the past is analyzed. It is demonstrated that the particle density and the energy density of cosmic rays in the Solar System in the distant past were much lower than the corresponding current values. The cosmic ray intensity modulation in the early heliosphere was especially strong in the case of low-energy particles. 相似文献