YNAO OpenIR  > 太阳物理研究组
Alternative TitleThe observational study on bipolar emerging active regions and magnetic helicity fluxes at the photospheric level
Thesis Advisor姜云春
Degree Grantor中国科学院研究生院(云南天文台)
Place of Conferral北京
Degree Discipline天体物理
Keyword磁螺度 新浮现区 光球层 不对称
Abstract磁螺度是表征磁场扭曲与环绕程度的物理量,它在太阳大气中衰减的极为缓慢。对光球层磁螺度进行测量表明,太阳南半球有更多的正磁螺度注入而北半球有更多的负磁螺度的注入。考虑到磁螺度在太阳大气中几乎不衰减,这种半球注入的不平衡将会导致磁螺度在各自所在半球的大气内不断的积累。这些在太阳大气中积累的磁螺度很可能会触发诸如耀斑、暗条/日珥爆发、日冕物质抛射等太阳活动。同时,在包括太阳爆发事件在内的各种太阳活动中,几乎都找到了磁螺度存在的证据。这些都表明,研究磁螺度对于解释太阳活动具有重要意义。 尽管磁螺度在太阳活中研究存在着重要的意义,关于太阳上磁螺度的起源,我们却知之甚少。而最近的一项关于磁螺度不对称性的研究为解决活动区磁螺度起源带来了曙光。但是这项研究急需解决一些问题,于是本文对这个发现进行了更深入的研究。本文将DAVE算法应用到SDO/HMI12分钟视向磁图,分别对9个偶极新浮现区的两极计算了磁螺度注入。计算结果验证了偶极浮现区磁螺度注入存对极性的偏好。但与之前研究中大部分活动区表现为先导极性注入更多的磁螺度这一结果不同,本文中6个活动区表现为后随极性有更多的磁螺度注入。于是本文提出,也许不能简单的认为偶极活动区的先导极性在磁螺度注入中更占优势。本文根据活动区磁通量之和的演化,将活动区的浮现过程分成了两个阶段,并发现磁螺度通量在两阶段有明显不同的表现。; Magnetic helicity,which measures the linkage and twist of magnetic field lines,dissipates very slowly in solar atmosphere. In each hemisphere, helicity has a preferred sign in injecting, namely, positive/negative sign in the southern/northern hemisphere. Considering the fact that the magnetic helicity cannot dissipate in corona, the injected helicity will be accumulated in corona, and thus may play a key role in various solar phenomena such as flares, filament/prominence eruptions, and coronal mass ejections. Moreover, observations have provided evidence of magnetic helicity in all kinds of solar activities including solar eruption events. These facts underline the importance in studying magnetic helicity. Though magnetic helicity play such an important role in studying solar activities, the origination of observed magnetic helicity in the solar atmosphere is not yet well understood. However, a recent study on the asymmetry of magnetic helicity sheds light on solving this problem. Yet, several problems need to be solved before such asymmetry being applied. Thus, I perform a further study on the asymmetry of magnetic helicity between two polarities of emerging bipolar ARs. In this paper, I apply differential affine velocity estimator (DAVE) to the Solar Dynamics Observatory (SDO)/Helioseismic and Magnetic Imager (HMI) 12-min line-of-sight magnetograms, and separately calculate the injected magnetic helicity for the leading and following polarities of 9 emerging bipolar active regions (ARs). This work confirm the previous results that emerging bipolar ARs have a polarity preference in injecting magnetic helicity. Contrast to the previous result that the leading polarity injected more magnetic helicity than the following one, 6 ARs studied here have a following polarity that inject more magnetic helicity. I argued that it might not appropriate to conclude that the leading polarity of bipolar emerging ARs have the tendency to inject more magnetic helicity. Based on the changes of unsigned magnetic flux, I divided the emergence process into two evolutionary stages. Obvious difference in the magnetic helicity flux can be seen in the two stages.
Subject Area天文学
Document Type学位论文
Recommended Citation
GB/T 7714
杨丹. 偶极浮现区与光球层磁螺度注入的观测研究[D]. 北京. 中国科学院研究生院(云南天文台),2014.
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