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1.
太阳活动起源研究(Ⅱ):太阳发电机理论 总被引：3，自引：1，他引：2
对试图解释太阳活动起源的太阳发电机理论作了综合评述。着重介绍了平均场运动学发电机理论，包括平均场的α效应，运用学的αΩ发电机和迁移发电机。讨论了MHD发电机和其它类型发电机的研究概况。 相似文献
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利用“多云模型”方法,从云南天文台二维多波段太阳光谱仪观测到的Ｈβ光谱资料中导出１９８９年８月１７日太阳西边缘的一个大的耀斑环系不同时间的视向速度场．为了解释观测速度场的主要特征,本文采用如下假设和近似：环内物质在太阳重力、磁场应力和环内气压梯度力联合作用下由环足沿螺旋磁力线上升运动．应用ＭＨＤ理论计算了它的理论速度场．通过两者的比较发现,计算出的速度场与第一时段的观测速度场基本相似,这似乎对耀斑物质蒸发模型提供了支持． 相似文献
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本文对非线性科学的两个重要分支－分形和混沌－在太阳物理学中的应用情况作了综述，主要内容包括：太阳活动混沌性的揭示；对太阳活动混沌性的可能解释－太阳非线性发电机理论；一些太阳现象的分形描述；耀斑的自组织临界行为研究。最后给出了作者对这一领域工作前景的展望。 相似文献
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太阳物理学中的分形和混沌 总被引：1，自引：0，他引：1
对非线性科学的两个重要分支；分形和混沌在太阳物理学中的应用情况作了综述信要内容包括；太阳活动混沌性的揭示；对太阳活动混沌性的可能解释－太阳非线性发电机理论；一些太阳现象的分形描述；耀斑的自组织临界行为研究，最后给出了作者对这一领域工作前景的展望。 相似文献
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本文介绍了太阳射电Ⅱ型爆发中的一种独特的精细结构现象－频率分裂，并对它的观测特征和理论解释做了总结，最后，还对现存众多的理论模型逐一作了讨论。 相似文献
7.
太阳剩余磁场是指形成于太阳主序星阶段之前，深藏在太阳辐射核内部的原始磁场。由于太阳内部高电导率和准静态等因素，其剩余磁场耗散相当缓慢，而得以保留至今。太阳剩余磁场的存在不仅能够解释太阳活动的很多不对称性现象，如南北不对称性、活动经度与活动穴、低纬度冕洞和Maunder极小期等，还能通过改变自激发发电机模型的边值条件而影响整个太阳表面磁场的分布与演化。从观测结果和理论模型两方面评述了太阳剩余磁场的研究成果及最新进展，并简单讨论了进一步努力的方向。 相似文献
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太阳磁场演变的起因之一——太阳的回磁效应 总被引：4，自引：0，他引：4
本指出太阳绕太阳系质心的角动量变率与黑子数年均值紧密相关，在１９００－１９８０年，当迟滞时间￣２年，相关系数高达０．８１，线性相在置信水平远高于９９．９％，并指出按太阳的回磁效应，可由太阳绕太阳系质心运动确定太阳基本磁偶极矩；它是太阳磁场演在太阳系内的起因之关键纽带。推测太阳内大部分物质的自转速度应该非常小；直接观测的较差自转，仅是表层现象，本叙述的基本理论，在对地球和其它行星乃至各至旋转天体 相似文献
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Hirokazu Yoshimura 《Journal of Astrophysics and Astronomy》2000,21(3-4):365-371
We briefly describe historical development of the concept of solar dynamo mechanism that generates electric current and magnetic
field by plasma flows inside the solar convection zone. The dynamo is the driver of the cyclically polarity reversing solar
magnetic cycle. The reversal process can easily and visually be understood in terms of magnetic field line stretching and
twisting and folding in three-dimensional space by plasma flows of differential rotation and global convection under influence
of Coriolis force. This process gives rise to formation of a series of huge magnetic flux tubes that propagate along iso-rotation
surfaces inside the convection zone. Each of these flux tubes produces one solar cycle. We discuss general characteristics
of any plasma flows that can generate magnetic field and reverse the polarity of the magnetic field in a rotating body in
the Universe. We also mention a list of problems which are currently being disputed concerning the solar dynamo mechanism
together with observational evidences that are to be constraints as well as verifications of any solar cycle dynamo theories
of short and long term behaviors of the Sun, particularly time variations of its magnetic field, plasma flows, and luminosity. 相似文献
12.
Ke-Ke Zhang Xin-Hao LiaoSchool of Mathematical Sciences University of Exeter EX QE UK kzhang@ex.ac.ukShanghai Astronomical Observatory Shanghai xhliao@center.shao.ac.cn 《中国天文和天体物理学报》2003,3(1):12-33
Generation of the Sun‘s magnetic fields by self-inductive processes in the solar electrically conducting interior, the solar dynamo theory, is a fundamentally important subject in astrophysics. The kinematic dynamo theory concerns how the magnetic fields are produced by kinematically possible flows without being constrained by the dynamic equation. We review a number of basic aspects of the kinematic dynamo theory, including the magnetohydrodynamic approximation for the dynamo equation, the impossibility of dynamo action with the solar differential rotation, the Cowling‘s anti-dynamo theorem in the solar context, the turbulent alpha effect and recently constructed three-dimensional interface dynamos controlled by the solar tachocline at the base of the convection zone. 相似文献
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《天文和天体物理学研究(英文版)》2021,(4)
The change of sound speed has been found at the base of the convection during the solar cycles,which can be used to constrain the solar internal magnetic field.We aim to check whether the magnetic field generated by the solar dynamo can lead to the cyclic variation of the sound speed detected through helioseismology.The basic configuration of magnetic field in the solar interior was obtained by using a Babcock-Leighton(BL) type flux transport dynamo.We reconstructed one-dimensional solar models by assimilating magnetic field generated by an established dynamo and examined their influences on the structural variables.The results show that magnetic field generated by the dynamo is able to cause noticeable change of the sound speed profile at the base of the convective zone during a solar cycle.Detailed features of this theoretical prediction are also similar to those of the helioseismic results in solar cycle 23 by adjusting the free parameters of the dynamo model. 相似文献
14.
S.-I. Akasofu 《Planetary and Space Science》1983,31(1):25-48
This paper emphasizes an effort to link processes which relate solar activity and magnetospheric disturbances in terms of energy transfer through a chain of four elements. In this view, each element is explicitly thought to be powered by a dynamo, namely the solar wind generation dynamo, the solar flare dynamo, the solar wind-magnetosphere dynamo and the auroral dynamo, respectively. Each dynamo powers a plasma acceleration process by the Lorentz force and the plasma flows thus generated are the solar wind, the flare-generated solar wind disturbance, the magnetospheric plasma convection and the ionospheric convection, respectively. Each plasma flow conveys the energy from one element to the next in the chain. Some of the kinetic energy of the photospheric plasma is eventually deposited in the polar ionosphere as heat energy. 相似文献
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The problem of whether the solar dynamo is quasi-periodic or chaotic is addressed by examining 1500 years of sunspot, geomagnetic and auroral activity cycles. We find sub-harmonics of the fundamental solar cycle period during the years preceding the Maunder minimum and loss of phase of the subharmonic on emergence from it. These phenomena are indicative of chaos. They indicate that the solar dynamo is chaotic and is operating in a region close to the transition between period doubling and chaos. Since Maunder type minima reoccur irregularly for millennia, it appears that the Sun remains close to this transition to and from chaos. We postulate this as a universal characteristic of solar type stars caused by feedback in the dynamo number. 相似文献
16.
E. P. Popova 《Astronomy Letters》2011,37(3):210-217
The behavior of dynamo waves in a two-layer medium is investigated in terms of the Parker dynamo model. The solar cycle duration
is shown to depend on the ratio of turbulent diffusivities in the layers. Meridional circulation has been incorporated into
the Parker system. An increase in the intensity of meridional flows is shown to decelerate the propagation of dynamo waves.
The minimum of solar magnetic activity can occur not only in the case of intense meridional circulation in both layers but
also when a difference in physical characteristics arises between the layers and the meridional flows are moderate. 相似文献
17.
Flux-transport type solar dynamos have achieved considerable success in correctly simulating many solar cycle features, and are now being used for prediction of solar cycle timing and amplitude. We first define flux-transport dynamos and demonstrate how they work. The essential added ingredient in this class of models is meridional circulation, which governs the dynamo period and also plays a crucial role in determining the Sun’s memory about its past magnetic fields. We show that flux-transport dynamo models can explain many key features of solar cycles. Then we show that a predictive tool can be built from this class of dynamo that can be used to predict mean solar cycle features by assimilating magnetic field data from previous cycles. 相似文献
18.
Dibyendu Nandy 《Solar physics》2004,224(1-2):161-169
Sun-like stars are known to display a wide variety of magnetic activity which is likely to be the signature of a hydromagnetic
dynamo mechanism working in stellar interiors. This dynamo mechanism has been studied extensively in the context of the Sun.
Here we take ideas and experiences gained from solar dynamo modeling and build upon it to study the inferred scaling laws,
involving stellar parameters, from observations of stellar magnetic activity. We also discuss how such a synthesis of theoretical
dynamo modeling of Sun-like stars and stellar cycle observations may help us reconstruct the long-term variability of the
Sun – an important ingredient for understanding the effects of solar forcing on space and global climate. 相似文献
19.
J. H. Piddington 《Astrophysics and Space Science》1982,87(1-2):477-478
This paper is largely a reply to Cowling's review of the present status of cosmic dynamo theory and its alternatives of primordial or fossil field models. Central is the question of turbulent diffusion, without which plasma dynamos will not work but primordial magnetic fields are retained. Turbulence does not shred or divide fields into small-scale elements as claimed; instead it creates these elements in addition to the large-scale field which remains after Ohmic diffusion has destroyed the small fields. The significance of the existence of a terrestrial dynamo is stressed and various objections to the existence of a solar-type dynamo are discussed, including the steady divergence of theory and observational evidence over a quarter century. Cowling's criticisms of the primordial field theory are discussed; these include turbulent diffusion, the timing of the solar magnetic cycle, and the importance attached to observations in active and quiet magnetic regions.Since this paper was communicated, a personal communication from Professor Cowling has partially resolved the difference of opinion about turbulent diffusion and its effects. This is discussed in a letter to the Editor, at the end of this volume, p. 477. 相似文献
20.
Some consequences of a nonlinear coupling between magnetic field and rotation are studied within a solar type 2D dynamo model for a spherical convective shell. The magnetic feedback on the rotation law produces two main effects. First, the torsional oscillations are excited. Second, a long-term amplitude modulation of the dynamo cycles is produced. The latter may be identified with the grand cycle of solar activity. The dynamo model seems to be in accord with the phase relations between the torsional and magnetic activity oscillations observed in the 11-year cycle as well as in the 55-year grand cycle. It, however, fails to reproduce the observationally suggested global decreasing trend in the equatorial rotation rate. 相似文献