共查询到19条相似文献，搜索用时 140 毫秒
1.
对“关于太阳线性无力场评注和快速傅氏分析法的应用的评论”一文,提出一些看法和补充,以增进对无力场计算太阳磁场问题的进一步的认识． 相似文献
2.
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
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太阳是与地球关系最为密切的天体.发生在日面上的剧烈爆发性活动可能对人类的生存环境产生巨大影响甚至是灾难性后果.包含太阳耀斑、暗条爆发和日冕物质抛射在内的太阳爆发活动是同一物理过程的不同表现形式,其能量来源于爆发前储存在日冕中的磁场自由能.因此,了解日冕磁场的3维结构是理解太阳爆发的触发机制以及活动区的稳定性等现象的前提.由于观测技术限制,目前尚无法对日冕磁场进行常规观测,因此发展了多种利用可常规观测的光球磁场来重建日冕磁场的方法.主要评述近10 yr来各种日冕磁场重建方法在研究太阳爆发活动中的应用. 相似文献
4.
研究发现,太阳自转速率的变化与太阳活动之间存在一定的联系,但是不同学者的研究结论存在着矛盾:有的认为两者为正相关,而有的却认为是负相关.究竟两者之间是什么关系,需要做进一步深入的分析.利用EEMD (Ensemble Empirical Mode Decomposition)等方法对太阳自转速率和太阳黑子数据序列进行相关关系以及相位关系的计算和分析,以探讨太阳自转速率变化与太阳活动之间的关系.研究发现:两者的长期趋势项分量呈显著负相关;在11 yr左右周期分量上,观测到的太阳自转速率滞后太阳黑子的变化约2 yr时,呈显著负相关关系,超前3 yr时呈现次显著的正相关;对太阳活动第12–23周各周内部太阳黑子与太阳自转速率的相关分析表明,两者的关系比较复杂,但负相关关系更为显著.这为进一步理解太阳活动变化与太阳自转速率变化之间的成因联系提供了新的依据. 相似文献
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莱曼阿尔法太阳望远镜(LST)是先进天基太阳天文台(ASO-S)卫星的载荷之一,它包括白光太阳望远镜(WST),全日面太阳成像仪(SDI)和日冕仪(SCI)等仪器. 1991年Kuhn, Lin和Loranz提出的方法(简称KLL方法)是WST和SDI在轨平场定标的方法之一.为了研究WST和SDI的平场定标精度对KLL方法的相邻位置时间间隔的敏感性,使用太阳动力学观测卫星(SDO)的日震和磁成像仪(HMI)及太阳大气成像仪(AIA)的全日面成像观测数据测试和分析在使用KLL方法时相邻位置时间间隔对所得平场精度的影响.结果显示在LST使用KLL方法进行平场定标时,相邻位置时间间隔越短越好.具体分析表明,WST平场精度对相邻位置采样时间间隔不敏感,而SDI时间间隔需要在240 s范围内.分析结果对卫星姿态调整到稳定所需的时间给出了一定限制. 相似文献
6.
毕少兰 《紫金山天文台台刊》2003,(2)
为了进一步探索太阳对流区的物理性质 ,我们利用高精度N的日震观测数据来研究太阳内部扰动磁场对低阶太阳P模振动的影响。对于一个时间相关的MHD湍流源 ,我们给出了导致频率变化的各种可能性。如果只考虑磁扰动的贡献 ,不同值的振动模的频率变化仅只是涨落磁场能谱的函数。我们发现频率的变化随着太阳内部磁场强度增加而变大 ,并且和太阳活动周期密切相关。我们的计算表明太阳磁活动导致的频率变化可达 0 .3μΗz。 相似文献
7.
太阳活动周期的小波分析 总被引：5，自引：0，他引：5
运用小波技术对太阳射电流量2800 MHz,太阳黑子数和太阳黑子面积数周期进行分析．其结果表明: (1)这3个系列的数据显示最显著的周期是10．69年,其他周期并不明显．(2)小波功率谱给出了全部时间-周期范围的功率谱变化,它显示了在某个周期处于某个时段的局部功率的变化,小波功率谱分析表明,小于1年的周期仅仅在太阳活动最大期附近比较明显．(3)太阳射电2800 MHz,太阳黑子数和太阳黑子面积数的几个周期(10．69年,5．11年, 155．5天)的小波功率谱比较相似,出现峰值的时间相同;曲线的起伏相似,周期越小,曲线起伏的频率越大． 相似文献
8.
太阳总辐照在23和24太阳活动周的显著周期分别为35 d和26 d,进而推断太阳的准旋转周期在23和24太阳活动周也分别为35 d和26 d.太阳总辐照在24周极小期的值可能与蒙德极小期的值相近.在一个太阳旋转周到几个月的时间尺度上,太阳黑子是引起太阳总辐照变化的主要原因,但不是唯一的原因;在几天到一个太阳旋转周的时间尺度上,太阳总辐照的变化与MgⅡ特征指数是不相关的. 相似文献
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稻城圆环阵太阳射电望远镜(Daocheng Solar Radio Telescope, DSRT)作为子午工程二期太阳-行星际探测子系统的重要部分, 工作在150--450MHz频段, 可提供高空间、高时间分辨率的太阳爆发亮温图像. 针对DSRT天线的高精度指向测量以及对指向误差批量标定和校正的需求, 首先根据DSRT独有的三轴座架系统, 通过四元数旋转变换法建立了天线3参数编码器零点误差模型; 然后提出了基于射电源的漂移扫描法获得16个单元天线功率方向图, 并根据2维方向图确定波束中心的方法精确测量了DSRT天线指向误差; 最后用最小二乘法拟合得到模型参数, 并通过天线控制软件重新调整各个轴的零点, 后对调整结果进行验证. 结果表明指向校正方法可靠有效, 校正后16个天线的指向精度为0.5$^\circ$之内, 明显优于校正前3.5$^\circ$的指向误差, 满足误差小于DSRT天线最高工作频率下的1/10波束范围内的要求. 相似文献
11.
《Chinese Astronomy and Astrophysics》2006,30(3):311-315
The paper “Comments on Solar Linear Force-free Field and Application of FFT Analysis”[19] made some comments on certain solar linear force-free field works and accordingly proposed an improved method of fast Fourier transform (FFT). Some viewpoints of this paper are worthy of reconsideration and it is necessary to clarify certain questions existing in it. We would also like to make some comments on its proposed method from the theoretical point of view. 相似文献
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Observational studies on solar ?ares with footpoints partially occulted by the solar limb provide an important method for diagnostics of coronal hard X-ray emissions. The statistics of hard X-ray sources in 71 such ?ares observed by RHESSI (Reuven Ramaty High-Energy Solar Spectroscopic Imager) show that the two kinds of hard X-ray sources proposed in previous studies (i.e., the sources with respectively a smaller and larger spatial separations between the thermal and non-thermal sources of coronal hard X-ray emissions) have no evident difference in the aspects of their photon spectra, images, light curves, GOES durations, etc. The area of the radiation region, the ?are's total thermal energy and GOES duration are well correlated with the distance of separation. These results support some uni?ed models of solar ?ares proposed in recent years, and indicate that the Masuda ?are is only a kind of special event, which does not possess the general features of coronal hard X-ray emissions 相似文献
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Observations of the solar full-disk were carried out by the Atmo- spheric Imaging Assembly (AIA) onboard the Solar Dynamics Observatory (SDO) with the Fe IX 171 Å line on 16th October 2010. The obtained high-quality data permit us to elaborate on the coronal loop oscillations. It is found that a major flare of GOES (Geostationary Operational Environmental Satellite) class M2.9 occurred in the active region NOAA 1112 during this period, which triggered a number of coronal loops on the solar surface to oscillate. Among them, there are two coronal loops exhibiting oscillations with different physical features. The oscillation of the coronal loop located at W492/S170 is a simple harmonic oscillation with a period of 385s, which abides by the oscillating equation of x = 2.2 sin[2π/385(t–768)], while the other located at W559/S142 is a damping oscillation with a period of 449s, and the oscillating equation is expressed by x = 24.8e - 2π/343 t sin[2π/449(t–1128)], where t is the observational time in units of second. 相似文献
15.
CHENG Li-bin LE Gui-ming LU Yang-ping CHEN Min-hao LI Peng YIN Zhi-qiang 《Chinese Astronomy and Astrophysics》2014
The solar flares, the speeds of shocks propagated in the solar-terrestrial space and driven by coronal mass ejections (CMEs), the heliographic longitudes and Carrington longitudes of source regions, and the geomagnetic storms, which are accompanied by the super solar proton events with a peak ?ux equal to or exceeding 10 000 pfu, have been studied by using the data of ground-based and space observations. The results show that the heliographic longitudes of source regions of super solar proton events distributed in the range from E30? to W75°. The Carrington longitudes of source regions of super solar proton events distributed in the two longitudinal belts, 130°∼220° and 260°∼320°, respectively. All super solar proton events were accompanied by major solar flares and fast CMEs. The averaged speeds of shocks propagated from the sun to the Earth were greater than 1 200 km/s. Eight super solar proton events were followed by major geomagnetic storms (Dst≤−100 nT), except that one super solar proton event was followed by a geomagnetic storm with the geomagnetic activity index Dst=−96 nT, a little smaller than that of major geomagnetic storms. 相似文献
16.
对于足点被日面边缘遮挡住的耀斑的观测研究是诊断日冕硬X射线辐射的一个重要方法.通过统计分析RHESSI (Reuven Ramaty High-Energy Solar Spectroscopic Imager)卫星观测到的71个此类耀斑硬X射线源发现,前人提出的两类源,即日冕X射线辐射中热辐射与非热辐射源区空间分离较小的源和分离较大的源,在能谱、成像、光变曲线以及GOES持续时间等方面都没有显著的区别,其中辐射区的面积、耀斑总热能以及GOES持续时间与分离距离之间有很好的相关性.这些结果支持近年来提出的一些耀斑统一模型.同时也表明Masuda耀斑只是一类非常特殊的事件,不具有日冕硬X射线辐射的一般特征. 相似文献
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Observations indicated that solar coronal mass ejections (CMEs) are closely asociated with reconnection-favored new flux emergence. By means of numerial simulations, a physical model of the emerging flux trigger mechanism for CMEs is proposed and explained well the observational results. Based upon this model, leaving the gravity and heat conduction out of consideration, the theoretical results of 2.5 dimensional numerical simulations indicate that whether a CME can be triggered depends on both the amount and the location of an emerging flux, besides its polarity orientation. Furthermore, the eruption and non-eruption regimes are presented in parameter space. By use of 15 filament eruption events in 2002 and 2003 and 44 non-eruption events in 2002, the results of a statistical study on the properties of emerging flux including its polarity orientation, its location and the amount of flux show that not all the emerging flux can make a filament to lose equilibrium and trigger the onset of a CME, The statistic results basically support the theoretical results of numerical simulations. This research provides useful information for the space weather forecast. 相似文献
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A statistical analysis of the type-III bursts observed by the spectrographs in the ranges of 625∼1500 MHz, 2600-3800 MHz, and 5200-7600 MHz during the 23rd solar cycle (from 2000 July to 2004 September) is carried out. The distribution of the type-III bursts, and their durations, frequency drift rates, polarization degrees and frequency bandwidths are given in this paper. The results indicate that the average values of the frequency drift rates and frequency bandwidths increase with the frequency. The average values of the durations and polarization degrees are neither constant nor uniformly varied over a broad frequency range. Most of type-III bursts are distributed in the range from 625 to 3800 MHz, and decrease with the frequency in number. This analysis shows that the places of electron acceleration and energy release are mainly in the decimetric range, and the characteristic of this frequency range is possibly related with the magnetic configuration at the decimeter wavelengths, as well as the electron acceleration in the magnetic reconnection site close to the main flare. However, there are also a considerable number of type-III bursts in the range of 5200-7600 MHz, it means that the sites of electron acceleration are widely distributed in the coronal region. The radiation mechanisms of type-III bursts at the centimeter-decimeter wavelengths include most probably the coherent plasma radiation and the emission process of electron cyclotron maser. 相似文献
19.
系统阐述了太阳中微子“亏缺”问题出现的背景,包括介绍标准太阳模型,太阳内部的相聚变反应,太阳中微子能谱和流量的理论估算,以及太阳中微子探测实验和结果。讨论了为解释太阳中微子“亏缺”而提出的各种非标准太阳模型以及近年来愈益受到重视的中微子振动问题。 相似文献