共查询到20条相似文献,搜索用时 218 毫秒
1.
The experiment with 10K-80 aboard the INTER-BALL-2 (which detects protons with energies > 7, 27–41, 41–58,
58–88, 88–180 and 180–300 MeV) registered six events of the solar energetic particle (SEP)
increase. These events are during the initial rise phase of the 23rd solar activity cycle. Solar flares with the SEP generation
are accompanied by coronal mass ejection (CME). Here we analyze the dynamics of the differential energy spectrum at different
phases of the SEP increase. 相似文献
2.
J. Javaraiah 《Journal of Astrophysics and Astronomy》2000,21(3-4):167-170
Using the data on sunspot groups compiled during 1879–1975, we determined variations in the differential rotation
coefficientsA andB during the solar cycle. The variation in the equatorial rotation rateA is found to be significant only in the odd numbered cycles, with an amplitude ∼ 0.01 μ rads-1. There exists a good anticorrelation between the variations of the differential rotation rateB derived from the odd and even numbered cycles, suggesting existence of a ‘22-year’ periodicity inB. The amplitude of the variation ofB is ∼ 0.05 μ rad s-1. 相似文献
3.
V. K. Verma 《Journal of Astrophysics and Astronomy》2000,21(3-4):173-176
We report here a study of various solar activity phenomena occurring in both north and south hemispheres of the Sun during
solar cycles 8–23. In the study we have used sunspot data for the period 1832–1976, flare index data
for the period 1936-1993, Hα flare data 1993–1998 and solar active prominences data for the period 1957–1998.
Earlier Verma reported long-term cyclic period in N-S asymmetry and also that the N-S asymmetry of solar activity phenomena
during solar cycles 21, 22, 23 and 24 will be south dominated and the N-S asymmetry will shift to north hemisphere in solar
cycle 25. The present study shows that the N-S asymmetry during solar cycles 22 and 23 are southern dominated as suggested
by Verma. 相似文献
4.
A possible scenario of polar magnetic field reversal of the Sun during the Maunder Minimum (1645–1715) is discussed
using data of magnetic field reversals of the Sun for 1880–1991 and the14
C content variations in the bi-annual rings of the pine-trees in 1600–1730 yrs. 相似文献
5.
A gradient based algorithm which divides arbitrary images into non-overlapping surface filling tiles of opposite polarity
is used to study the flux and size distributions of large scale magnetic flux concentrations in solar and heliospheric observatory
(SoHO) magnetograms. The mean absolute flux and size of the concentrations at the considered scale is found to be about 1.7
× 1018Mx and 5.2Mm for both polarities. The form of the flux distribution is characterized by a skewness of α3 = 4.9 and a kurtosis of α4 = 42.8. The fall in the distribution in the range 6.5 × 1017 Mx to 5×1018 Mx is described by an exponential fit, in agreement with a model for the sustenance of quiet region flux. 相似文献
6.
The solar corona – one of the most spectacular celestial shows and yet one of the most challenging puzzles –
exhibits a spectrum of structures related to both the quiet Sun and active regions. In spite of dramatic differences in appearance
and physical processes, all these structures share a common origin: they are all related to the solar magnetic field. The
origin of the field is beneath the turbulent convection zone, where the magnetic field is not a master but a slave, and one
can wonder how much the coronal magnetic field “remembers” its dynamo origin. Surprisingly, it does.
We will describe several observational phenolmena that indicate a close relationship between coronal and sub-photospheric
processes. 相似文献
7.
S. Vauclair 《Journal of Astrophysics and Astronomy》2000,21(3-4):323-329
The inversion of helioseismic modes leads to the sound velocity inside the Sun with a precision of about 0.1 per cent. Comparisoons
of solar models with the “seismic sun” represent powerful tools to test the physics: depth of the convection
zone, equation of state, opacities, element diffusion processes and mixing inside the radiative zone. We now have evidence
that microscopic diffusion (element segregation) does occur below the convection zone, leading to a mild helium depletion
in the solar outer layers. Meanwhile this process must be slowed down by some macroscopic effect, presumably rotation-induced
mixing. The same mixing is also responsible for the observed lithium depletion. On the other hand, the observations of beryllium
and helium 3 impose specific constraints on the depth of this mildly mixed zone. Helioseismology also gives information on
the internal solar rotation: while differential rotation exists in the convection zone, solid rotation prevails in the radiative
zone, and the transition layer (the so-called “tachocline”) is very small. These effects are discussed,
together with the astrophysical constraints on the solar neutrino fluxes. 相似文献
8.
S. C. Tripathy Brajesh Kumar Kiran Jain A. Bhatnagar 《Journal of Astrophysics and Astronomy》2000,21(3-4):357-360
Using intermediate degreep-mode frequency data sets for solar cycle 22, we find that the frequency shifts and magnetic activity indicators show a “hysteresis”
phenomenon. It is observed that the magnetic indices follow different paths for the ascending and descending phases of the
solar cycle while for radiative indices, the separation between the paths are well within the error limits. 相似文献
9.
In this paper we present complete two-dimensional measurements of the observed brightness of the 9th November 1990Hα flare, using a PDS microdensitometer scanner and image processing software MIDAS. The resulting isophotal contour maps, were
used to describe morphological-cum-temporal behaviour of the flare and also the kernels of the flare. Correlation of theHα flare with SXR and MW radiations were also studied. 相似文献
10.
I. S. Veselovsky A. V. Dmitriev A. V. Suvorova M. V. Tarsina 《Journal of Astrophysics and Astronomy》2000,21(3-4):423-429
The cyclic evolution of the heliospheric plasma parameters is related to the time-dependent boundary conditions in the solar
corona. “Minimal” coronal configurations correspond to the regular appearance of the tenuous, but hot
and fast plasma streams from the large polar coronal holes. The denser, but cooler and slower solar wind is adjacent to coronal
streamers. Irregular dynamic manifestations are present in the corona and the solar wind everywhere and always. They follow
the solar activity cycle rather well. Because of this, the direct and indirect solar wind measurements demonstrate clear variations
in space and time according to the minimal, intermediate and maximal conditions of the cycles. The average solar wind density,
velocity and temperature measured at the Earth’s orbit show specific decadal variations and trends, which are of
the order of the first tens per cent during the last three solar cycles. Statistical, spectral and correlation characteristics
of the solar wind are reviewed with the emphasis on the cycles. 相似文献
11.
M. Sobotka M. Vzquez M. Snchez Cuberes J. A. Bonet A. Hanslmeier 《Journal of Astrophysics and Astronomy》2000,21(3-4):289-292
Simultaneous time series of broad-band images of two active regions close to the disk center were acquired at the maximum
(0.80Μm) and minimum (1.55Μm) continuum opacities. Dark faculae are detected in images obtained as weighted intensity differences between both wave-length
bands. The elements of quiet regions can be clearly distinguished from those of faculae and pores in scatter plots of brightness
temperatures. There is a smooth transition between faculae and pores in the scatter plots. These facts are interpreted in
terms of the balance between the inhibition of convective energy transport and the lateral radiative heating. 相似文献
12.
We compute the signs of two different current helicity parameters (i.e., αbest andH
c) for 87 active regions during the rise of cycle 23 The results indicate that 59% of the active regions in the northern hemisphere
have negative αbest and 65% in the southern hemisphere have positive. This is consistent with that of the cycle 22. However, the helicity parameterH
cshows a weaker opposite hemispheric preference in the new solar cycle. Possible reasons are discussed. 相似文献
13.
We study the effects of incorporating magnetic buoyancy in a model of the solar dynamo—which draws inspiration
from the Babcock-Leighton idea of surface processes generating the poloidal field. We present our main results here. 相似文献
14.
Takashi Sakurai 《Journal of Astrophysics and Astronomy》2000,21(3-4):389-395
Recent advances in the understanding of the quiet corona and coronal holes are reviewed. The review is based on long-term
accumulation of data from eclipse observations, coronagraph observations, helium 10830 å spectroheliograms, and
X-ray observations. 相似文献
15.
M. H. Gokhale 《Journal of Astrophysics and Astronomy》2000,21(3-4):155-160
Data on sunspot groups have been quite useful for obtaining clues to several processes on global and local scales within the
sun which lead to emergence of toroidal magnetic flux above the sun’s surface. I present here a report on such
studies carried out at Indian Institute of Astrophysics during the last decade or so. 相似文献
16.
J. T. Nolte A. S. Krieger A. F. Timothy G. S. Vaiana M. V. Zombeck 《Solar physics》1976,46(2):291-301
This atlas shows the boundary locations of the coronal holes observed in soft X-rays (2–32, 44–54 Å) by the AS & E X-ray spectrographic telescope on Skylab. The data are presented as tracings of the boundaries as they appeared when the holes were near central meridian.Center for Astrophysics - Harvard College Observatory, Smithsonian Astrophysical Observatory. 相似文献
17.
Arnab Rai Choudhuri 《Journal of Astrophysics and Astronomy》2000,21(3-4):373-377
This review provides a historical overview of how research in kinematic solar dynamo modeling evolved during the last few
decades and assesses the present state of research. The early pioneering papers assumed the dynamo to operate in the convection
zone. It was suggested in the 1980s that the dynamo operates in a thin layer at the bottom of the convection zone. Some researchers
in recent years are arguing that the poloidal field is produced near the surface—an idea that goes back to Babcock
(1961) and Leighton (1969). 相似文献
18.
19.
The Ulysses Unified Radio and Plasma Wave Experiment (URAP) has observed Langmuir, ion-acoustic and associated solar type
III radio emissions in the interplanetary medium. Bursts of 50–300 Hz (in the spacecraft frame) electric field
signals, corresponding to long-wavelength ion-acoustic waves are often observed coincident in time with the most intense Langmuir
wave spikes, providing evidence for the electrostatic decay instability. Langmuir waves often occur as envelope solitons,
suggesting that strong turbulence processes, such as modulational instability and soliton formation, often coexist with weak
turbulence processes, such as electrostatic decay, in a few type III burst source regions. 相似文献
20.
D. M. Rust 《Journal of Astrophysics and Astronomy》2000,21(3-4):177-183
Solar filaments are discussed in terms of two contrasting paradigms. The standard paradigm is that filaments are formed by
condensation of coronal plasma into magnetic fields that are twisted or dimpled as a consequence of motions of the fields’
sources in the photosphere. According to a new paradigm, filaments form in rising, twisted flux ropes and are a necessary
intermediate stage in the transfer to interplanetary space of dynamo-generated magnetic flux. It is argued that the accumulation
of magnetic helicity in filaments and their coronal surroundings leads to filament eruptions and coronal mass ejections. These
ejections relieve the Sun of the flux generated by the dynamo and make way for the flux of the next cycle. 相似文献