共查询到18条相似文献，搜索用时 187 毫秒
1.
2.
3.
张勤 《中国天文和天体物理学报》1990,(1)
在太阳活动预报中,预报因子的选取和处理对预报效果影响甚大。本文在云台原有的平均综合指数基础上,运用模糊识别方法,给出了一种模糊识别综合指数,它能更好地表征太阳日面活动区的活动特征。这种方法简单、方便,较充分地利用了预报因子中所含有的有用信息,从而使识别预报率有所提高。 相似文献
4.
本文根据太阳活动区AR5395中存在旋转运动特征,建立了一个扭转的共生磁流管模型,从一组完整的磁流体动力学方程组研究活动区底部的旋转运动储存能量。通过数值方法研究了三维流场和磁场的耦合效应。结果表明活动区底部的旋转运动产生的扰 相似文献
5.
在太阳耀斑区磁场和电流研究方面，文中将着重介绍太阳横向磁场方位的确定，太阳活动区磁场的非热性表示、太阳耀斑前后的活动区磁场变化、以及耀斑核块与活动区纵向电流密度极大点位置的关系等几个重要问题的研究现状。 相似文献
6.
质子活动与太阳黑子群 总被引：1，自引：1，他引：0
本文对太阳活动第２１周、２２周（１９７６年－１９９２年间）９７个质子活动区进行统计分析，包括活动区的面积、型别、磁结构、半影纤维等，结果表明：７５％的质子耀斑产生于面积为５００≤Ｓｐ≤３０００单位的黑子群中；耀斑爆发前一天及后一天活动区面积有显著减少，质子活动区含δ复杂磁结构的占７０％；具有半影旋涡形态的质子活动区中，约７７％的耀斑发生在旋涡黑子出现以后。 相似文献
7.
本文对太阳活动第２１周、２２周（１９７６年—１９９２年间）９７个质子活动区进行统计分析，包括活动区的面积、型别、磁结构、半影纤维等，结果表明：７５％的质子耀斑产生于面积为５００≤Ｓｐ≤３０００单位的黑子群中；耀斑爆发前一天及后一天活动区面积有显著减少；质子活动区含δ复杂磁结构的占７０％；具有半影旋涡形态的质子活动区中，约７７％的耀斑发生在旋涡黑子出现以后。 相似文献
8.
在太阳活动区的物理研究中,特别是在二维动力学光谱分析中,迫切需要相应活动区的磁图资料。本文介绍了在太阳光谱仪的入射狭缝后安装一种新型偏振器进行活动区二维磁场观测的新方法。这种方法不仅能获得日面上任一点的磁场强度,且可快速获得活动区的纵向场磁图。除此之外,还可利用多条谱线的同时观测,获得有关磁力线管结构等方面的资料。 相似文献
9.
太阳线性无力场评注和快速傅氏分析法的应用 总被引：1，自引：0，他引：1
首先对30年来用无力场计算太阳活动区磁场方法作了一些评注，特别研究了线性无力场解中的几个误区，提出了准线性无力场方法并探讨了快速傅氏变换在线性无力场计算中的应用，以2000年9月15日NOAA 9165活动区磁场为例，应用3种不同的方法计算出磁力线走向，然后同紫金山天文台赣榆观测站观测的精细Hα图形对比。 相似文献
10.
本文分析了分别由Nakagawa等、Seehafer以及Chiu等给出的常α无力磁场的几种不同的外推方法,并把它们应用于同一个太阳活动区——M11976区——加以检验和比较.对于需要活动区的三维磁场的场合,本文提出了关于这些不同方法的选择和使用方面的建议. 相似文献
11.
Shu-Rong Zhou Guang-Li Huang Zheng-Zhong Han Cheng Fang 《Astrophysics and Space Science》2002,280(4):369-380
In this paper, the theory and method of fuzzy mathematics are applied to forecast the activity of solar active regions. According
to the correlation between flares and several solar activity indices of active regions, the membership functions are constructed
to comprehensively evaluate and predict the activity of solar active regions. By means of data reduction and analysis, some
comparatively accurate results of prediction have been obtained. The accuracy of predicting the activity grades of active
regions is higher than 97%. This implies that the method of fuzzy forecast is a good one for solar activity prediction.
This revised version was published online in July 2006 with corrections to the Cover Date. 相似文献
12.
We present an analysis of 2634 Ca II K‐line full‐disk filtergrams obtained with the 15‐cm aperture photometric full‐disk telescope at Big Bear Solar Observatory during the period from 1996 January 1 to 2005 October 24. Using limb darkening corrected and contrast enhanced filtergrams, solar activity indices were derived, which are sensitive to the 11‐year solar activity cycle and 27‐day rotational period of plages around active regions and the bright chromospheric network. The present work extends an earlier study (solar cycle 22), which was based on video data. The current digital data are of much improved quality with higher spatial resolution and a narrower passband ameliorating photometric accuracy. The time series of chromospheric activity indices cover most of solar cycle 23. One of the most conspicuous features of the Ca II K indices is the secondary maximum in late 2001/early 2002 after an initial decline of chromospheric activity during the first half of 2001. We conclude that a secular trend exists in the Ca II K indices, which has its origin in the bright chromospheric network and brightenings related to decaying active regions. Superposed on this secular trend are the signatures of recurring, long‐lived active regions, which are clusters of persistent and continuously emerging magnetic flux. Such features are less visible, when the activity belts on both side of the equator are devoid of the brightenings related to decaying active regions as was the case in October/November 2003 at a time when a superactivity complex including several naked‐eye sunspots emerged (© 2010 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim) 相似文献
13.
The increase in the amount of solar data provided by new satellites makes it necessary to develop methods to automate the detection of solar features. Here we present a method for automatically detecting active regions in solar extreme ultraviolet (EUV) images using a series of steps. Initially, the bright regions in the image are segmented using seeded region growing. In a second phase these bright regions are clustered into active regions. Partition-based clustering (both hard and fuzzy) and hierarchical clustering are compared in this work. The aim of the clustering phase is to associate a group to each segmented region in order to reduce the total number of active regions. This facilitates the documentation or subsequent monitoring of these regions. We use two indicators to validate the partitioning: i) the number of detected clusters approximates the number of active regions reported by the National Oceanic and Atmospheric Administration (NOAA) and ii) the area that defines each cluster overlaps with the area of an active region of NOAA. Experiments have been performed on over 6000 images from SOHO/EIT (195 Å). The best results were obtained using hierarchical clustering. The method detects a set of active regions in an image of the solar corona that successfully matches the number of NOAA regions. We will use these regions to perform real-time monitoring and flare detection. 相似文献
14.
We summarize studies of helical properties of solar magnetic fields such as current helicity and twist of magnetic fields in solar active regions (ARs), that are observational tracers of the alpha-effect in the solar convective zone (SCZ). Information on their spatial distribution is obtained by analysis of systematic mag-netographic observations of active regions taken at Huairou Solar Observing Station of National Astronomical Observatories of Chinese Academy of Sciences. The main property is that the tracers of the alpha-effect are antisymmetric about the solar equator. Identifying longitudinal migration of active regions with their individual rotation rates and taking into account the internal differential rotation law within the SCZ known from helioseismology, we deduce the distribution of the effect over depth. We have found evidence that the alpha-effect changes its value and sign near the bottom of the SCZ, and this is in accord with the theoretical studies and numerical simulations. We discuss 相似文献
15.
Yan-Xia Zhang Yong-Heng ZhaoNational Astronomical Observatories Chinese Academy of Sciences Beijing 《中国天文和天体物理学报》2003,3(2):183-190
The sizes of astronomical surveys in different wavebands are increasing rapidly. Therefore, automatic classification of objects is becoming ever more important. We explore the performance of learning vector quantization (LVQ) in classifying multi-wavelength data. Our analysis concentrates on separating active sources from non-active ones. Different classes of X-ray emitters populate distinct regions of a multidimensional parameter space. In order to explore the distribution of various objects in a multidimensional parameter space, we positionally cross-correlate the data of quasars, BL Lacs, active galaxies, stars and normal galaxies in the optical, X-ray and infrared bands. We then apply LVQ to classify them with the obtained data. Our results show that LVQ is an effective method for separating AGNs from stars and normal galaxies with multi-wavelength data. 相似文献
16.
Helioseismic techniques such as ring-diagram analysis have often been used to determine the subsurface structural differences
between solar active and quiet regions. Results obtained by inverting the frequency differences between the regions are usually
interpreted as the sound-speed differences between them. These in turn are used as a measure of temperature and magnetic-field
strength differences between the two regions. In this paper we first show that the “sound-speed” difference obtained from
inversions is actually a combination of sound-speed difference and a magnetic component. Hence, the inversion result is not
directly related to the thermal structure. Next, using solar models that include magnetic fields, we develop a formulation
to use the inversion results to infer the differences in the magnetic and thermal structures between active and quiet regions.
We then apply our technique to existing structure inversion results for different pairs of active and quiet regions. We find
that the effect of magnetic fields is strongest in a shallow region above 0.985R
⊙ and that the strengths of magnetic-field effects at the surface and in the deeper (r<0.98R
⊙) layers are inversely related (i.e., the stronger the surface magnetic field the smaller the magnetic effects in the deeper layers, and vice versa). We also find that the magnetic effects in the deeper layers are the strongest in the quiet regions, consistent with the
fact that these are basically regions with weakest magnetic fields at the surface. Because the quiet regions were selected
to precede or follow their companion active regions, the results could have implications about the evolution of magnetic fields
under active regions. 相似文献
17.
G. A. Romero † C. E. Cappa ‡ 《Monthly notices of the Royal Astronomical Society》2009,395(4):2095-2102
We present a study of active star-forming regions in the environs of the H ii region Sh2-205. The analysis is based on data obtained from point source catalogues and images extracted from the Two-Micron All-Sky Survey (2MASS), Midcourse Space Experiment ( MSX ) and IRAS surveys. Complementary data are taken from a CO survey. The identification of primary candidates for star-formation activity is made following colour criteria and a correlation with molecular gas emission.
A number of star-formation tracer candidates are projected on to two substructures of the H ii region: SH 148.83–0.67 and SH 149.25–0.00. However, the lack of molecular gas related to these structures casts doubt on the nature of the sources. Additional infrared sources may be associated with the H i shell centred at ( l , b ) = (149°0', −1°30') .
The most striking active area was found in connection with the H ii region LBN 148.11–0.45, where star-formation candidates are projected on to molecular gas. The analytical model of the 'collect and collapse' process shows that star-formation activity could have been triggered by the expansion of this H ii region. 相似文献
A number of star-formation tracer candidates are projected on to two substructures of the H ii region: SH 148.83–0.67 and SH 149.25–0.00. However, the lack of molecular gas related to these structures casts doubt on the nature of the sources. Additional infrared sources may be associated with the H i shell centred at ( l , b ) = (149°0', −1°30') .
The most striking active area was found in connection with the H ii region LBN 148.11–0.45, where star-formation candidates are projected on to molecular gas. The analytical model of the 'collect and collapse' process shows that star-formation activity could have been triggered by the expansion of this H ii region. 相似文献
18.
Temporal variations of the subsurface meridional flow with the solar cycle have been reported by several authors. The measurements
are typically averaged over periods of time during which surface magnetic activity existed in the regions where the velocities
are calculated. The present work examines the possible contamination of these measurements due to the extra velocity fields
associated with active regions plus the uncertainties in the data obtained where strong magnetic fields are present. We perform
a systematic analysis of more than five years of GONG data and compare meridional flows obtained by ring-diagram analysis
before and after removing the areas of strong magnetic field. The overall trend of increased amplitude of the meridional flow
towards solar minimum remains after removal of large areas associated with surface activity. We also find residual circulation
toward the active belts that persists even after the removal of the surface magnetic activity, suggesting the existence of
a global pattern or longitudinally-located organized flows. 相似文献