共查询到20条相似文献，搜索用时 281 毫秒
1.
V. M. Grigoryev 《Solar physics》1993,148(2):389-391
A space experiment project is proposed, with the main purpose of obtaining 3-dimensional images of the solar atmosphere. We give a list of problems and objectives which can be resolved through the space-borne solar stereoscope. 相似文献
2.
Theoretical considerations lead to a solar cosmic ray diffusion coefficient which varies with heliolongitude in a stream-structured solar wind. By solving numerically the time dependent convection-diffusion equation for the particle transport we investigate the effect of the azimuthal variation of the diffusion coefficient on intensity-time profiles as seen by a stationary observer. Depending on the position of the observer relative to the solar wind stream at the time of flare occurrence, completely different intensity-time profiles will be observed. When the spacecraft is at the time of the flare occurrence right at the leading edge of a solar wind stream, the large mean free path leads to rapid steepening of the initial phase of the intensity profile. The longitudinally decreasing mean free path 1 day in front of the leading edge will lead to intensity-time profiles similar to long-time injection events if the event occurs before the stationary observer enters the flux tubes with the decreasing diffusion coefficient. 相似文献
3.
V.A. Kovalenko 《Planetary and Space Science》1988,36(12):1343-1358
An analysis has been made of the origin of long-term variations in flux density of solar wind particles (nv) for different velocity regimes. The study revealed a relationship of these variations to the area of the polar coronal holes (CH). It is shown that within the framework of the model under development, the main longterm variations of nv are a result of the latitude redistribution of the solar wind mass flux in the heliosphere and are due to changes in the large-scale geometry of the solar plasma flow in the corona.
A study has been made of the variations of nv for high speed solar wind streams. It is found that nv in high speed streams which are formed in CH, decreases from minimum to maximum solar activity. The analysis indicates that this decrease is attributable to the magnetic field strength increase in coronal holes.
It has been found that periods of rapid global changes of background magnetic fields on the Sun are accompanied by a reconfiguration of coronal magnetic fields, rapid changes in the length of quiescent filaments, and by an increase in the density of the particle flux of a high speed solar wind. It has been established that these periods precede the formation of CH, corresponding to the increase in solar wind velocity near the Earth and to enhancement of the level of geomagnetic disturbance. 相似文献
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5.
Z. S. Akhtemov V. G. Fainshtein N. N. Stepanian G. V. Rudenko 《Bulletin of the Crimean Astrophysical Observatory》2012,108(1):4-12
H-alpha flares accompanied by the X-radiation f ?? 10?6 wm?2 in power are examined; 2331 flares were registered during the first half of the 23rd solar cycle (1997?C2000). The specific power of the X-radiation of the flares monotonically doubles from the minimum to the maximum of the sunspot. An increase in the number of flares in each solar rotation is nonmonotonic and disproportional to the relative number of sunspots. Several longitudinal intervals with increased flare activity can be distinguished in the entire time interval of five to ten rotations. The longitudinal distributions of flares and boundaries of the sector structures of a large-scale magnetic field differ considerably. This confirms the existence of two types of zero lines; the first type is determined by active regions, and the second one is determined by large-scale structures with weak magnetic fields. The flares concentrate near Hale??s zero lines of the first type. 相似文献
6.
Richard G. Teske 《Solar physics》1971,17(1):76-88
Soft X-radiation between 8–12 Å was found to be emitted from the Sun at the time of four optically-identified major systems of loop prominences. The peak emission rates and time-integrated X-ray energies are very similar for three of the events while the fourth appeared to emit X-rays only weakly. The data are not consistent with a compression-condensation model for the loops, and support the fast-proton injection model. Proton injection may take place on a long time scale. 相似文献
7.
Richard G. Teske 《Solar physics》1971,19(2):356-378
Soft solar X-rays in the wavelength interval 8–12 Å were observed from OSO III. The totality of the observations that were made between 9 March, 1967, and 18 May, 1968, is summarized graphically and compared to the course of solar activity as observed at other wavelengths, with particular emphasis upon visible activity. 相似文献
8.
John W. Evans 《Solar physics》1968,3(2):344-345
Pairs of spectra exposed simultaneously in the yellow and ultraviolet show exactly the same solar granulation in the two colors. This is contrary to Vassilyeva's earlier results. The difference is probably due to her neglect of atmospheric dispersion. 相似文献
9.
T. W. Cole 《Solar physics》1973,30(1):103-110
The techniques of power spectral analysis are used to determine significant periodicities in the annual mean relative sunspot numbers. The main conclusion is that a period of 10.45 yr is very basic and can be associated with an excitation of new solar cycles. When combined with a period of 11.8 yr, associated here with the free-running length of a solar cycle, the mean cycle length of 11.06 yr and a phase variation of 190 yr are explained. Similarly the amplitude variations with periods 88 and 59 yr (previously described as the 80-yr cycle) are due to an amplitude modulation of the solar cycle by a period of 11.9±0.3 yr. The results dispute several associations of planetary position and solar activity.Radiophysics Publication RPP 1647, January, 1973. 相似文献
10.
We have analyzed magnetograph observations of the 5-min oscillations. We find that most of the oscillatory power is concentrated in space and frequency. Interference effects where these concentrations overlap can explain some of the variations in amplitude of the oscillation.Of the National Bureau of Standards and University of Colorado. 相似文献
11.
This study aims at investigating surface magnetic flux participation among different types of magnetic features during solar cycle 24. State-of-the-art observations from SDO/HMI and Hinode/SOT are combined to form a unique database in the interval from April 2010 to October 2015. Unlike previous studies, the statistics presented in this paper are feature-detection-based. More than 20 million magnetic features with relatively large scale, such as sunspot/pore, enhanced and quiet networks, are automatically detected and categorized from HMI observations, and the internetwork features are identified from SOT/SP observations. The total flux from these magnetic features reaches 5.9×10~(22) Mx during solar minimum and2.4 × 10~(23) Mx in solar maximum. Flux occupation from the sunspot/pore region is 29% in solar maximum.Enhanced and quiet networks contribute 18% and 21% flux during the solar minimum, and 50% and 9% flux in the solar maximum respectively. The internetwork field contributes over 55% of flux in the solar minimum, and its flux contribution exceeds that of sunspot/pore features in the solar maximum. During the solar active condition, the sunspot field increases its area but keeps constant flux density of about 150 G,while the enhanced network follows the sunspot number variation showing increasing flux density and area,but the quiet network displays decreasing area and somewhat increasing flux density of about 6%. The origin of the quiet network is not known exactly, but is suggestive of representing the interplay between mean-field and local dynamos. The source, magnitude and possible importance of ‘hidden flux' are discussed in some detail. 相似文献
12.
Currents in the solar atmosphere and a theory of solar flares 总被引：1，自引：0，他引：1
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14.
Charles J. Pellerin Jr. 《Solar physics》1975,41(2):449-458
A detailed study of the charge composition of heavy solar cosmic rays measured in the January 25, 1971 solar flare including differential fluxes for the even charged nuclei from carbon through argon is presented. The measurements are obtained for varying energy intervals for each nuclear species in the energy range from 10 to 35 MeV nucleon?1. In addition, abundances relative to oxygen are computed for all the above nuclei in the single energy interval from 15 to 25 MeV nucleon?1. This interval contains measurements for all of the species and as a result requires no spectral extrapolations. An upper limit for the abundance of calcium nuclei is also presented. These measurements, when combined with other experimental results, enable the energy dependence of abundance measurements as a function of nuclear charge to be discussed. It is seen that at energies above about 10 MeV nucleon?1, the variations of abundance ratios are limited to about a factor of 3 from flare to flare, in spite of large variations in other characteristics of these solar events. 相似文献
15.
We apply the generalized Lomb–Scargle (LS) periodogram, proposed by Zechmeister and Kurster, to the solar neutrino data from Super-Kamiokande (Super-K) using data from its first five years. For each peak in the LS periodogram, we evaluate the statistical significance in two different ways. The first method involves calculating the False Alarm Probability (FAP) using non-parametric bootstrap resampling, and the second method is by calculating the difference in Bayesian Information Criterion (BIC) between the null hypothesis, viz. the data contains only noise, compared to the hypothesis that the data contains a peak at a given frequency. Using these methods, we scan the frequency range between 7–14 cycles per year to look for any peaks caused by solar rotation, since this is the proposed explanation for the statistically significant peaks found by Sturrock and collaborators in the Super-K dataset. From our analysis, we do confirm that similar to Sturrock et al, the maximum peak occurs at a frequency of 9.42/year, corresponding to a period of 38.75 days. The FAP for this peak is about 1.5% and the difference in BIC (between pure white noise and this peak) is about 4.8. We note that the significance depends on the frequency band used to search for peaks and hence it is important to use a search band appropriate for solar rotation. However, The significance of this peak based on the value of BIC is marginal and more data is needed to confirm if the peak persists and is real. 相似文献
16.
It was shown by Zheleznyakov and Zlotnik (1980a, b) that in complex configurations of solar magnetic fields (in hot loops above the active centres, in neutral current sheets in the preflare phase, in hot X-ray kernels in the initial flare phase) a system of cyclotron lines in the spectrum of microwave radiation is likely to be formed. Such a line was obtained by Willson (1985) in the VLA observations at harmonics of the electron gyrofrequency. This communication interprets these observations on the basis of an active region model in which thermal cyclotron radiation is produced by hot plasma filling the magnetic tube in the corona above a group of spots. In this model the frequency of the recorded 1658 MHz line corresponds to the third harmonic of electron gyrofrequency, which yields the magnetic field (196 ± 4) G along the magnetic tube axis. The linewidth f/f 0.1 is determined by the 10% inhomogeneity of the magnetic field over the cross-section of the tube; the line profile indicates the kinetic temperature distribution of electrons over the tube cross-section with the maximum value 4 × 106 K. Analysis shows that study of cyclotron lines can serve as an efficient tool for diagnostics of magnetic fields and plasma in the solar active regions and flares. 相似文献
17.
We show that smoothed time series of 7 indices of solar activity exhibit significant solar cycle dependent differences in
their relative variations during the past 20 years. In some cases these observed hysteresis patterns start to repeat over
more than one solar cycle, giving evidence that this is a normal feature of solar variability. Among the indices we study,
we find that the hysteresis effects are approximately simple phase shifts, and we quantify these phase shifts in terms of
lag times behind the leading index, the International Sunspot Number. Our measured lag times range from less than one month
to greater than four months and can be much larger than lag times estimated from short-term variations of these same activity
indices during the emergence and decay of major active regions. We argue that hysteresis represents a real delay in the onset
and decline of solar activity and is an important clue in the search for physical processes responsible for changing solar
emission at various wavelengths.
The High Altitude Observatory is sponsored by the National Science Foundation. 相似文献
18.
In this study, we look for the mid‐term variations in the daily average data of solar radius measurements made at the Solar Astrolabe Station of TUBITAK National Observatory (TUG) during solar cycle 23 for a time interval from 2000 February 26 to 2006 November 15. Due to the weather conditions and seasonal effect dependent on the latitude, the data series has the temporal gaps. For spectral analysis of the data series, thus, we use the Date Compensated Discrete Fourier Transform (DCDFT) and the CLEANest algorithm, which are powerful methods for irregularly spaced data. The CLEANest spectra of the solar radius data exhibit several significant mid‐term periodicities at 393.2, 338.9, 206.5, 195.2, 172.3 and 125.4 days which are consistent with periods detected in several solar time series by several authors during different solar cycles. The knowledge relating to the origin of solar radius variations is not yet present. To see whether these variations will repeat in next cycles and to understand how the amplitudes of such variations change with different phases of the solar cycles, we need more systematic efforts and the long‐term homogeneous data. Since most of the periodicities detected in the present study are frequently seen in solar activity indicators, it is thought that the physical mechanisms driving the periodicities of solar activity may also be effective in solar radius variations (© 2009 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim) 相似文献
19.
We attempt to correlate all of the available solar-neutrino data with the strong magnetic fields these neutrinos encounter in the solar interior along their Earth-bound path. We approximate these fields using the photospheric, magnetograph-measured flux from central latitude bands, time delayed to proxy the magnetic fields in the solar interior. Our strongest evidence for anticorrelation is for magnetic fields within the central ±5° solar-latitude band that have been delayed by 0.85 ± 0.55 yr. Assuming a neutrino-magnetic interaction, this might indicate that interior fields travel to the solar surface in this period of time. As more solar-neutrino flux information is gathered, the question of whether this result arises from a physical process or is merely a statistical fluke should be resolved, providing that new data are obtained spanning additional solar cycles and that correlation studies focus on these same regions of the solar magnetic field. 相似文献
20.
S. O. Ifedili 《Solar physics》1974,39(1):233-241
The upper limit on the solar neutron flux from 1–20 MeV has been measured, by a neutron detector on the OGO-6 satellite, to be less than 5 × 10–2 n cm–2 s–1 at the 95% confidence level for several flares including two flares of importance 3B and a solar proton event of importance 3B. The measurements are consistent with the models proposed by Lingenfelter (1969) and by Lingenfelter and Ramaty (1967) for solar neutron production during solar flares. The implied upper limit on the flux of 2.2 MeV solar gamma rays is about the same as the 2.2 MeV flux observed by Chupp et al. (1973). 相似文献