共查询到17条相似文献，搜索用时 375 毫秒
1.
We present an analysis of plasma and magnetic field data acquired by the Ulysses spacecraft on May 1994. Our study is motivated by the result of Poletto et al. (1996) who found some evidence for a peak in the power spectrum of magnetic pressure at a frequency 2 × 10–5 Hz, during that period. A re-evaluation of the plasma pressure power spectrum, on the basis of better data than used in the previous work, gives only marginal evidence for a peak at that frequency. If both spectra had excess power in the same spectral range, one might hypothesize that the Pressure Balanced Structures (PBS) detected in the data trace periodically distributed coronal structures which maintain their identity up to large distances. A careful data analysis, however, shows that this interpretation is hardly tenable. Hence, we consider the alternative hypotheses that the observed PBS are either a bundle of magnetic flux tubes, with no characteristic periodicity, in pressure equilibrium with the ambient, or the manifestation, at large distances, of waves generated close to the Sun. To prove the latter case, we made a test simulation of the evolution with heliocentric distance of an ensemble of Alfvén and slow mode waves, generated close to the Sun, and show that structures similar to those we analyzed may form in the interplanetary medium. Our simulations also seem to show that together with PBS, magnetic holes, frequently observed in the Ulysses data, could also originate from the nonlinear evolution of large amplitude slow waves in quasi-perpendicular propagation. We conclude that the observed PBS most likely arise via an in situ generation mechanism, rather than being remnants of solar structures. 相似文献
2.
《天文研究与技术》1990,(4)
The hourly values of three magnetic components from 9 stations in the china Meri dian chain are used to analyse the characteristics of the storm on March 13-14, 1989, and to construct the equivalent ionospheric current systems. The contribution from the ring currents and field-aligned currents to the magnetic disturbances are recognized. 相似文献
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《天文研究与技术》1990,(4)
AR5629 is a super—active region It had 21 X—ray bursts(class M or higher)accom-panied with optical bursts which importances greater than one or higher within the AR.These events centered the days from 12,Aug.to 17,Aug.in 1989(16 events).Sunspotswithin the AR,consist of a big main spot and a satellite spot,which located at 17S,75L,can be seen on the solar disk from 4,Aug.to 16,Aug.On 14,Aug.,it reached its maxi- 相似文献
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《紫金山天文台台刊》1998,(2)
We discussed the 2 - D structure and the distribution of magnetic field in comet Halley. We further compared our 1 - D results of distribution along the Giotto encounter trajectory with magnetic field measurements experiment on Giott. 相似文献
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《天文研究与技术》1990,(4)
Five segments of sheared magnetic polarity inversion lines with their positions relative to the main spots in AR 5395 are indentified. The observational' results of fine structure of sunspots and the chromospheric filaments associated with the identified sheared ineversion lines show that (1) magnetic shear is intimately tied to 5 spot and spiral spots, (2) the sheared field over the inversion line usually contains a chromospheric filament, (3) orientation of fibrils in the filament lying over a sheared inversion line are often evidently not perpendicular to the inversion line, (4) twisting sometimes occurs in some filaments tracing sheared lines. The inverstigation of the flares in AR 5395 observed with 26cm solar telescope during 9-16 March shows that (1) all of the flares with optical importance≥ 1 or X-ray class≥M1 occur quite near the sheared inversion lines, (2) a 3N/ X1.2 flare on 13 March, the largest one, occured on both sides of the segment A, the longest and most complicated sheared inversi 相似文献
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《天文研究与技术》1990,(4)
This paper has analysed the general solar-Terrestrial effect of major event in March, 1989 from 7 parameters using same time scale.The largest magnetic storm from AA index is compared on 8 stations of Changchun (43 ° 49 ′ 38 ″ N), Beijing (40 ° 02′ 22 ″ N), Wuhan(30 ° 31 ′ 39 ″ N) and Guangzhou (23 ° 05′ 34 ″ N) in China and Newport of Washington (48. 263 ° N), Boulder of Colorado (40. 138 ° N), Fredericksburg of VA (38. 205 ° N) and Norda of Mississippi in U. S. A.The ARMA (p, q) Autoregressive slide average model is used to simulate the geomagnetic storm data in 4 stations of China. The periodicity analysis, characteristic root and equation are used. The different models and characters are shown and explained. 相似文献
11.
《天文研究与技术》1990,(4)
The super-active region AR 5395 emerged from the high latitude zone, rarely. Thephotospheric spots was a big group with complex magnetic fields, i.e., δ-structure. OnMarch 13, 1989 the AR area came to its maximum; 3589 units (1unit=10~(-6) Hemisphere). The umbra with S polarity, which presented U-shape, sur- 相似文献
12.
《天文研究与技术》1990,(4)
Using the solar magnetic field telescope on Huairou Station, We obtained some data of high-resolution photosphere vector magnetic field and chromosphere velocity field from Auguest 7, 1989 to Auguest 17, 1989. From these data, and obvious fact has been found. This is the permeations of the opposite magnetic polarity configuration near the natural lines. These permeations are probably the mechanism of triggering flare.Potential field configuration obtained under some assumptions accords well with the configuration of flare loops. 相似文献
13.
《天文研究与技术》1990,(4)
This paper deals with a discussion of the morphological correlation between the photospheric transversal magnetic field (PTMF) observed at Beijing Observatory and the penumbral filaments (PF) observed at Yunnan Observatory in eight areas of the largest active region AR5395 for the period of 9-15 March 1989. The morphological correlation is rouphly divided in three grades:"consistence", "approach"and "cross", "consistence" means that the difference of the azimuthal angles of PTMF and PF is smaller than 20 ° ; "approach" means that the difference is in the range of 20 ° and 40 ° ; "cross" means that the difference is more than 40 ° . The statistical conclusions are: 相似文献
14.
We have studied the temporal variations in the north–south asymmetries of the differential rotation parameters A, B, and the mean rotation rate , by determining their values from Greenwich data for sunspot groups (1879–1976) in the northern and southern hemispheres, during moving time intervals of lengths 3 yr and 5 yr, successively displaced by 1 yr. The variation in the north–south asymmetry (
) of is similar to the variation in the asymmetry (B
) of B but with opposite sign. These variations of
and B
may represent components of an anti-symmetric torsional oscillation which are in opposite phase with each other.The FFT and MEM analyses of the temporal variations of B
,
, and the north–south asymmetry (A
) of A, show existence of significant periodicities: 45.5 ± 11.5 yr,21.3 ± 4.5 yr, 13.3 ± 1.5 yr, and 10.5 ± 0.5 yr. These analyses also show a few other possible periodicities in A
, B
, and
. All these periodicities are also seen in the north–south asymmetry of sunspot activity (with similar relative magnitudes). The 22-yr periodicity was seen in even-parity modes of magnetic field inferred from sunspot data. 相似文献
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We obtained a set of well-observed 2D H spectral data of a 1N/M1.5 flare from the Solar Tower of Nanjing University. Using the H spectra, the sites of electron precipitation and high coronal pressure have been found, and the Doppler velocity was calculated from the red asymmetry of the H emission line by use of the bisector method. The current density distribution was also computed from magnetic field measurements. We have coaligned the H spectroheliograms and the magnetograms. It was found that the sites of electron precipitation were at the edge of a main current area. The sites of red asymmetry coincided with those of high coronal pressure. The flare reached its maximum in the magnetic shear region, though it began in a weak magnetic field. Several flare models are discussed to see which one could satisfy the observation. 相似文献
17.
Fine structure of brightness inhomogeneities with I r.m.s. = 2.9% was discovered on the extreme limb of the Sun on the best quality white-light photographs obtained at the Soviet Stratospheric Solar Observatory. The concept is that temperature inhomogeneities are responsible for the limb structure. The real value T r.m.s. = 109K is required to explain our observations. Another possible explanation is that small-scale magnetic flux tubes with the realistic filling factor f* = 1% are the source of the limb brightness fluctuations. 相似文献