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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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太阳发电机理论主要解释太阳磁场的起源和演化,是太阳物理中最基本、最重要的问题之一.对它的研究不仅具有重要的科学价值,而且对空间天气的预测和空间技术的发展有一定的影响.随着日震学的发展,该理论也得到了很大改进。从相关观测入手,综述了发电机理论需解释的观测事实,以及为发电机理论提供约束的太阳内部动力学结构;介绍了基本理论和近来的主流模型,并指出尚待解决的问题和进一步的努力方向。 相似文献
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许多行星(如木卫三,水星,地球,木星和土星)和恒星(如太阳)具有内部磁场。对这些磁场的存在和变化的解释对行星科学家和天体物理学家是一个巨大的挑战。本文试图总结行星和恒星的导电流体内部磁流体力学研究的新近发展和困难。一般由热对流驱动的流动通过磁流体力学过程产生并维持在行星和恒星中的磁场。在行星中磁流体力学过程强烈地受到转动,磁场和球几何位型的综合影响。其动力学的关键方面涉及科里奥利力和洛伦兹力间的相互作用。在太阳中其流线,即处于对流层的薄的剪切流层在太阳的磁流体力学过程中扮演了一个基本的角色,并由之产生了11年太阳黑子周期。本文也给出了一个新的非线性三维太阳发电机模型。 相似文献
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利用怀柔太阳磁场望远镜,我们对太阳宁静区光球和色球磁场进行了观测。日面中心到边缘的观测表明,太阳宁静区中的小尺度磁结构在从光球到色球的扩展过程中变化不大。日面边缘的观测表明,小尺度磁结构的水平分量在光球和色球都不大。对极区和赤道边缘纵向磁场的比较发现,极区磁场与赤道边缘磁场有着不同的磁结构特性 相似文献
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太阳大气中磁重联的MHD数值模拟 总被引:1,自引:0,他引:1
回顾了近30年太阳大气中磁重联过程的MHD数值模拟工作取得的进展。着重描述了在验证理论模型,解释观测现象,以及研究各种因素对重联的影响三个方面的成果,如快速磁重联,太阳耀斑机制及色球,日冕中的各种爆发现象等。指出了在数值模拟中应注意的几个问题,并对该领域今后的发展作了简要的展望。 相似文献
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关于日冕中稳恒态磁流体力学流动的一个定理 总被引:1,自引:1,他引:0
本报告了在日冕或其他天体物理环境中,沿磁力线流动的稳恒态磁流体力学流动的一个定理和一个重要关系。它们是利用宏观动能密度对磁能密度的比例导出的。 相似文献
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太阳磁场是研究太阳物理的关键。目前对太阳磁场的精确测量只限于光球层。对日冕磁场结构的了解,则多是以观测的光球磁场作为边界条件,在某种理论模型下进行外推。势场模型、线性无力场模型和非线性无力场模型是无力场假设下的三种理论外推模型。文章介绍了太阳磁场理论外推的基本方法和最新进展,和对三种模型中使用较多的外推方法,列举了它们在天文研究中的一些应用,同时也简略讨论了外推方法中存在的一些问题。 相似文献
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Coronal Magnetic Flux Rope Equilibria and Magnetic Helicity 总被引:1,自引:0,他引:1
1 INTRODUCTIONObservations show that the magnetic helicity of solar magnetic structures has a predominantsign in each hemisphere of the Sun, positive in the southern hemisphere and negative in thenorthern, regardless of the solar cycle (Rust, 1994). The magnetic helicity is strictly conservedin the frame of ideal MHD (WOltjer, 1958), and approximately conserved in the presence ofresistive dissipation and magnetic reconnection in a highly conductive plajsma (Taylor, 1974;Berger, 1984; H… 相似文献
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Hong-Qi Zhang National Astronomical Observatories Chinese Academy of Sciences Beijing 《中国天文和天体物理学报》2006,6(1):96-112
We present the evolution of magnetic field and its relationship with mag- netic(current)helicity in solar active regions from a series of photospheric vector magnetograms obtained by Huairou Solar Observing Station,longitudinal magne- tograms by MDI of SOHO and white light images of TRACE.The photospheric current helicity density is a quantity reflecting the local twisted magnetic field and is related to the remaining magnetic helicity in the photosphere,even if the mean current helicity density brings the general chiral property in a layer of solar active regions.As new magnetic flux emerges in active regions,changes of photospheric cur- rent helicity density with the injection of magnetic helicity into the corona from the subatmosphere can be detected,including changes in sign caused by the injection of magnetic helicity of opposite sign.Because the injection rate of magnetic helicity and photospheric current helicity density have different means in the solar atmosphere, the injected magnetic helicity is probably not proportional to the current helicity den- sity remaining in the photosphere.The evidence is that rotation of sunspots does not synchronize exactly with the twist of photospheric transverse magnetic field in some active regions(such as,delta active regions).They represent different aspects of mag- netic chirality.A combined analysis of the observational magnetic helicity parameters actually provides a relative complete picture of magnetic helicity and its transfer in the solar atmosphere. 相似文献
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1 INTRODUCTIONRecently Bao, Zhang, Ai, and Zhang (1999), using Huairou vector magnetograph data,have shown that the average current helicity (h.) or the curreflt helicity imbalance ph of activeregions change rapidly after so1ar flares. Up'an the onset of flares it tends to decrease for a fewhours and then to increase again, whereas ifQ some cases the flare promotes an increase in thecurrent helicity The observations led to tbe fol1owing conclusions: (1) raPid and substantialchanges of c… 相似文献
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A. V. Mordvinov 《Solar physics》2007,246(2):445-456
A comparative analysis of solar and heliospheric magnetic fields in terms of their cumulative sums reveals cyclic and long-term
changes that appear as a magnetic flux imbalance and alternations of dominant magnetic polarities. The global magnetic flux
imbalance of the Sun manifests itself in the solar mean magnetic field (SMMF) signal. The north – south asymmetry of solar
activity and the quadrupole mode of the solar magnetic field contribute the most to the observed magnetic flux imbalance.
The polarity asymmetry exhibits the Hale magnetic cycle in both the radial and azimuthal components of the interplanetary
magnetic field (IMF). Analysis of the cumulative sums of the IMF components clearly reveals cyclic changes in the IMF geometry.
The accumulated deviations in the IMF spiral angle from its nominal value also demonstrate long-term changes resulting from
a slow increase of the solar wind speed over 1965 – 2006. A predominance of the positive IMF B
z
with a significant linear trend in its cumulative signal is interpreted as a manifestation of the relic magnetic field of
the Sun. Long-term changes in the IMF B
z
are revealed. They demonstrate decadal changes owing to the 11/22-year solar cycle. Long-duration time intervals with a dominant
negative B
z
component were found in temporal patterns of the cumulative sum of the IMF B
z
. 相似文献