空间科学学报

1987 Vol. 7, No. 1

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The Formation of Neutral Current Sheets and the Associated Loop Coronal Transients

Hu You-qiu, Jin Shu-ping

1987, 7(1): 1-9. doi: 10.11728/cjss1987.01.001

Abstract(1488) PDF 603KB(743)

Abstract:
Under a bipolar background magnetic field, a neutral current sheet is liable to form in between the new emerging magnetic field and the background owing to an eruption of opposite magnetic flux. Based on the ideal magnetohydrodynamic equations, this paper has made a numerical study of the above Formation of current sheets, considering the interaction between the magnetic field and the coronal plasma. The result shows that a subsonic eruption gives rise to a four-region structure from inside to outside: (1) a low-temperature, high-density prominence, consisting of the erupted material and located at the most-interior-region, (2) a low-temperature rarefaction region right next to the erupted prominence, (3) a high-temperature, high-density loop formed by the concentration of both erupted and coronal material into the neutral current sheet, and (4) a forerunner around the loop with the density slightly higher than the coronal background, due to the fast magnetosonic wave. The above mentioned structure is conformed with the observed features of typical loop coronal transients. Consequently, the eruption of opposite magnetic flaxes under the bipolar background field is most likely an important mechanism for triggering such kind of transients.

Large Scale Coronal Magnetic Field and Coronal Holes in the Declining Phase of Solar Cycles

Zhao Xue-pu, Zhang Lei

1987, 7(1): 10-17. doi: 10.11728/cjss1987.01.010

Abstract(1506) PDF 518KB(848)

Abstract:
The variation of the solar wind speed with the Carrington longitude in the declining phase of solar cycles 18 and 19 are deduced by using geomagnetic data. Referring to the sector structure of the IPM inferred from the geomagnetic observations in the polar cap, the polarity of the coronal magnetic field and the heliospheric colatitude and the Carrington longitude of the dipole-like poles are inferred in the same periods. The average results are compared with that of the solar cycle 20.

A Comparison Between Hard X-ray, Soft X-ray, Microwave Burst Images and Ha Isopfaote Map of Flare on November 5, 1980

Shi Zhong-xian, Wang Jing-xiu

1987, 7(1): 18-28. doi: 10.11728/cjss1987.01.018

Abstract(1554) PDF 607KB(649)

Abstract:
Filtergrams of 1B/M1-M4 Ha flare starting at 22^h25^m of November 11, 1980 are digitized, and isophote lines are drawn in order to compare with hard X-ray, soft X-ray and microwave burst images. The following results are revealed.1. For the first maximum, high energy electrons do not penetrate the chromosphere. Ha flare may be caused by heat conduction from 10⁷K-10⁸K hot plasma which generated hard and soft X-ray emissions.2. The second maximum can be infered to be caused by bremsstralung of high energy electrons. The Ha flare maximum occured later than that of X-ray burst for less than 5 seconds.3. During the flash phase the area and the intensity of Ha emission enhanced simultaneously.4. From the changes of transverse magnetic fields outlined by Ha fibrils, 10³¹ engs magnetic energy is estimated to be released in this flare.

A Study of the Energy Deposits in Flaring Atmosphere with Semiempirical Models of Flares

Fang Cheng, Gan Wei-qun

1987, 7(1): 29-38. doi: 10.11728/cjss1987.01.029

Abstract(1556) PDF 624KB(902)

Abstract:
Using the time-varying semiempirical models for two flares (one is classified as a SBflare and the other a 2Bflare), which were deduced from the spectral data obtained with the solar tower telescope of Nanjing University, the radiative loss at different phases of the flares are computed and compared with the energy deposits due to electron beam bombardment and X-ray radiation. The results show that the variation of chromospheric radiative loss during the flares is more than one order of magnitude. It is also shown that during the impulsive phase of the flares the heating due to the electron beam bombardment is very efficient, but for the gradual phase of the flares, the energy deposits mechanism due to X-ray is a better one than that due to electron beam in order to explain the observational results, whereas near the intensity maximum of the flares, both X-ray and electron beam have their contributions. The results indicate that the heating in the lower chromosphere and the upper photosphere, especially for large flares, can be caused neither by X-ray radiation nor by electron beam bombardment. It seems that there are some other mechanism to transpot the deposit energy from the upper part of the atmosphere to the lower part. This study also shows that time-varying models of flares are good tools in the investigation of the flare energy balance.

The Relationship Between the Particle-Energy Spectral Index and The Microwave-Burst Power Spectral Index

Yao Jin-xing, Liu Yan

1987, 7(1): 39-45. doi: 10.11728/cjss1987.01.039

Abstract(1617) PDF 470KB(848)

Abstract:
In this paper we suggest a method of estimating the electron-energy spectral index (6) from the microwave radiation power spectral index (a). We have also given a tesult of the correlation statistics between the radio radiation power spectral index and the proton-energy spectral index, of which correlation coefficient is 0.70. The results of calculating 6 for the burst of August 7,1972 show that electron-energy spectrum can be approximately represented by a power-law distribution at the rise time before the peak, but deviated from the power-law distribution after the peak. The range of the values of 6 is about 0.4-3.6 at the impulsive phase of the bursts. The results of the computation also show that there is no second accelaration step presented for the white light flare of August 7, 1972. This conclusion is supported by the result of the correlation statistics, and it is also consistant with the SMM observations during the 21th cycle SMY.

The Time Evolution Effects in Fermi Acceleration by Shock Waves (Ⅲ)

Li Ting-yi, Mao Dinng-yi, Wang De-yu

1987, 7(1): 46-51. doi: 10.11728/cjss1987.01.046

Abstract(1723) PDF 385KB(737)

Abstract:
In this paper, a study of the time evolution processes of Fermi acceleration by shock waves in the case of the diffusion coefficient of particles varies with momentum is made. The evolution of the energy spectra and the kinetic energy of accelerated particles with various temporal and spacial distributions of source particles are obtained. The results of calculation show that the energetic particles are not as easy to be accelerated as comparied with the case of the diffusion coefficient independent on momentum. The average kinetic energy increases with time according to the law of-t^2/n, provided that the diffusion coefficitnt varies with the momentum in the form of x-Pⁿ.

A Synthetical Study of Convection Pattern by Using Results from GEOS-2 S301 and S329 Experiments

Zi Min-yun

1987, 7(1): 52-58. doi: 10.11728/cjss1987.01.052

Abstract(1481) PDF 533KB(597)

Abstract:
Asynthetical study by using the results from the GEOS-2 electron gun experiment S329 and the relaxation sounding experiment S301 is made to discuss the convection pattern in the magnetosphere. The comparison and synthesis are carried out with the help of the Volland's semi-empirical model, which can connect the convection electric field with the shape and dimension of the cold plasma boundary (i. e. the plasmapause). The results of both experiments show a Kp-dependance of the westward rotation of the convection pattern and demonstrate the applicability of the Volland's model in describing the convectionselectric field around the synchronous orbit. The two observations arc contradictory in predicting the size cf the plasma-pause when Kp is high. This is possibly caused by the complexity of the dynamic processes around the plasmapause. The processes concerned and the dawndusk asymmetry of the E-field observed by the electron gun experiment are worthy of further study.

A Method of Determining Ground Distance of the Separate Scatterer Echo in the HF Backscatter lonogram

Jiao Pei-nan, Du Jun-hu

1987, 7(1): 59-64. doi: 10.11728/cjss1987.01.059

Abstract(1397) PDF 441KB(712)

Abstract:
In this paper, a method of determining the ground distance of the separate scattering sources from the HFbackscatter ionogram is given. It is assumed that the scattering traces of the source are in a parabola which is tangential to the minimum time-delay curve, the ground distance of a separate fixed scatterer can be calculated. It is based on the data of the minimum time delay curve and three pairs of the data of group path and frequency of the traces in the backscatter ionogram of a single backscatter sounding station. The results of the experimental test indicated that the errors of the results calculated with the method presented here are not more than 3%.

The Solar Proton Events and the Disturbances of Atmospheric Ozone

Ye Zong-hai, Xue Shun-sheng, Wang Lian-ying

1987, 7(1): 65-72. doi: 10.11728/cjss1987.01.065

Abstract(1489) PDF 571KB(978)

Abstract:
The relationship between the solar proton events above importance 1 and the atmospheric ozone content over four latitude regions from 1960 to 1982 is studied in this paper. The results show that the solar proton events of importance 1 and 2 have no influence [O₃] appreciably over middle and low latitude regions. Only the solar proton events of importance 3 can influence [O₃] significantly, and there is obvious latitude effect. The proton events above importance 1 can influence [O₃] over the polar region. The disturbances of [O₃] increase with the increase of importances of the proton events. Usually [O₃] starts decreasing when solar proton events occur and the decrease lasts for several days. The minimum of the decrease occurs on the fourth day after the solar proton event. For reasons given above it is proved that the solar proton event is an important factor disturbing ^-O₃] . The disturbances of [O₃] caused by the solar proton events in winter are more prominent than in summer. The results show the general influence of proton events on [O₃] over different latitudes, and it can be well interpreted theoretically.

Thermoluminescence Study on Bo County Meteorite

Wang Kui-ren, Liu Jing-fa, Yang Hai-tao

1987, 7(1): 73-77. doi: 10.11728/cjss1987.01.073

Abstract(1843) PDF 357KB(2118)

Abstract:
In this paper the results of thermoluminecence (TL) study on Bo County meteorite are reported. Temperature gradient in the meteorite, produced by heating during its atmospheric passage, is 34.2°C/mm in head, 24.8°C/mm in side. The temperature profiles of the meteorite is closed to the Barwell meteorite, and more reasonably consistent with the steady-state solution to the heat conductivity equation in a case of the ablation rate of 0.10 cm/sec. According to the TLcurve of the meteorite the parameter Ln (LT/HT) is 1.30. So the meteorite belong to type A.

The Distribution of Elements in the Metal Phase of Some Chinese Ordinary Chondrites

Chen Yong-heng, Sun Yong-jun, Wang Dao-de

1987, 7(1): 78-84. doi: 10.11728/cjss1987.01.078

Abstract(1415) PDF 503KB(1004)

Abstract:
The concentrations of Fe, Ni, Co, Cu, Cr, Mn, Ga, Ge, Ir, Au and As in the metal phases of Jinlin (H₃), Xinyang (H₅), Zhaodong (L₅), Guangrao (L_6-5) and Dongtai (LL₆) ordinary chondrites in China are determined by instrumental neutron activation analysis, For each meteorite various metallic fractions were analyzed: <20 mesh, 20 -40 mesh, >40 mesh and so on. In terms of these results, the elemental distribution and fractional trends and the processes determining the composition of the metal phase are discussed.