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太阳日浪、喷流及其相关现象的研究
The Study of Solar Surges, Jets and Their Associated Phenomena
【作者】 陈华东;
【作者基本信息】 中国科学院研究生院(云南天文台) , 天体物理, 2008, 博士
【摘要】 本文综述了太阳日浪、喷流及其相关现象到目前所取得的一些观测和理论成果,并介绍了本人在攻读博士学位期间对日浪和喷流的时空关系以及它们的物理起源等问题所做的(或参与做的)研究工作。本论文包括三个部分,综述部分(第一章),工作部分(第二章到第四章)和问题和展望部分(第五章)。论文的主要成果归纳如下:1.通过对七个接连发生在活动区卫星黑子之上的Hα日浪事件进行研究,我们发现:它们的足根处有异极性磁流的浮现、汇聚和相互对消活动。相应地,在光球白光像上,一个小的卫星黑子在大约两个小时的时间内浮现、消退并消失。在形态上,所有的日浪都显示几乎线性的喷发结构。它们的动力学特征,比如横向移动速度、最大投影长度和寿命等,在很大的范围内变化。它们分别是30—200 km s-1、38000—220000 km和从几分种到几十分钟之间。相应地,与这些日浪相关的微耀斑的强度也不同。大体上,具有较大速度或投影长度的日浪似乎伴随着有更多能量释放的过程。在这些事件之前,一个小的Hα拱暗条出现在日浪的根部,并且连接着异极性的磁流元。在这些连续的日浪活动中,它没有整体地爆发,而是逐渐地消失。它在日浪中的作用很像一个包含着冷的等离子体并与周围磁场进行重联的偶极磁流。在1600A波段上,三个曰浪展示出由亮喷流和附近小耀斑环(flaring loop)所组成的复合结构。这就提供了它们磁重联起源的直接证据。通过仔细对比,我们发现小拱暗条、紫外喷流和小耀斑环的足点正与那些相互作用的光球纵向磁流相对应。这些观测结果支持日浪和喷流的磁重联模型。2.研究2002年7月29日发生在太阳活动区NOAA 10044中的一个远紫外喷流和Hα暗条爆发事件,我们发现:它们伴随着一个M4.8级的较大耀斑。在Hα的偏带观测上,一个小暗条在耀斑期间从活动区的中性线上爆发。同时,两个远紫外亮环随着暗条爆发升起和膨胀。随后,冷和热的远紫外等离子体抛射共同形成了远紫外喷流。这两个分量在空间上相互分离,并持续了25分钟左右。在白光日冕像上,一个狭窄的CME与这个远紫外喷流很好地对应。我们没有发现光球层上有明显的浮现磁流。相反地,我们注意到在事件之前有明显的黑子消退和异极性磁流之间的对消现象。RHESSI的硬X射线观测证明,沿着主要的磁中性线有磁重联的发生。基于这些结果,我们认为所有观测到的动力学现象,包括远紫外喷流、暗条爆发、耀斑和CME等,都与低层大气中的磁流对消密切相关。3.利用多波段(Hα,远紫外和软X射线)的观测,我们对3个在大约70分钟的时间内重复发生的日浪进行了研究。它们于2000年11月3日发生在太阳宁静区。这些相似的日浪与同一根部处的小耀斑相关,但是它们真正的足点在空间上却与耀斑是分离的。每个日浪都由一个冷的Hα和热的远紫外或软X射线分量组成。这两个分量不仅在时间上而且在空间上都显示了不同的演化过程。远紫外喷流具有略微汇聚的形状、经历较复杂的发展演化、显示清晰的扭曲结构并好像喷向外层空间。然而,Hα日浪要小一些并仅仅沿着喷流的边缘分布。日浪总是出现在喷流之后,但与出现在亮喷流中的远紫外暗分量相对应。这些日浪活动与足根处的两对浮现偶极子和它们所导致的磁流对消密切相关,并与日浪的磁重联模型相一致。
【Abstract】 In this thesis,some observational and theoretical progresses in the study of solar surges,jets and other related dynamical phenomena are reviewed,and my works about the spatial and temporal relationships between surges and jets and their physical origin are introduced during the period of my specializing in PHD. The thesis consists of three parts.The first chapter is review,the second to the fourth ones are my works and the last chapter is the problems and prospects. Our main contributions are as follows:1.Studying seven successive Hαsurge events,we found that:at their base region,the opposite photospheric longitudinal fluxes emerged,converged and were canceled by each other.Correspondingly,a small satellite spot emerged, decayed and disappeared during a period of about 2 hours in the white-light observations. The dynamic properties of the surges,such as the transverse velocity, projected maximum length and lifetime,varied in wide ranges.They are 30-200 km s-1,38 000-220 000 km and from several to tens of minutes,respectively. Correspondingly,the intensities of their correlated microflares were different too. Prior to these surge events,a small Hαarch filament connecting the opposite flux elements was found at the base region.Instead of erupting completely,it gradually disappeared during the surges.Its role in the surge activities is very like a bipolar flux,which contained the cool plasma and reconnected with the ambient magnetic fields.In 1600(?),three surge events exhibited the composite structures of bright jets and nearby small flaring loops,which provides direct evidence of magnetic reconnection origin of the surges.A careful comparison revealed that the ends of the arch filament,the UV jets and the small flaring loops just corresponded to the interacting longitudinal fluxes in the photosphere. These observational results support the magnetic reconnection model of surges and jets.2.we present a detailed study of an EUV jet and the associated Hαfilament eruption in a major flare in the active region NOAA 10044 on 2002 July 29.In the data of Hαline wings,a small filament was found to erupt out from the magnetic neutral line of the active region during the flare.Two bright EUV loops were observed rising and expanding with the filament eruption,and both hot and cool EUV plasma ejections were observed to form the EUV jet.The two thermal components spatially separated from each other and lasted for about 25 minutes.In the white-light corona data,a narrow coronal mass ejection(CME) was found to well respond to this EUV jet.We cannot found obvious emerging flux on the photosphere accounting for the filament eruption and the EUV jet. On the contrary,significant sunspot decaying and magnetic flux cancellation due to collision of opposite flux before the events were noticed.Based on the hard X-ray data by RHESSI,which showed the evidence of magnetic reconnection along the main magnetic neutral line,we think that all the observed dynamical phenomena,including the EUV jet,filament eruption,flare and CME,should have a close relation to the flux cancellation in the low atmosphere.3.We analyzed multi-wavelength observations of three surges with a recurrent period of about 70 min in Hα,EUV,and soft X-ray,which occurred in the quiet-sun region on 2000 November 3.These homologous surges were associated with small flares at the same base,but their exact footpoints were spatially separated from the flare.Each surge consisted of a cool Hαcomponent and a hot, EUV or soft X-ray component,which showed different evolutions not only in space but also in time.The EUV jets had slightly converging shapes,underwent more complicate development,showed clearly twisting structures,and appeared to open to space.The Hαsurges,however,were smaller and only traced the edges of the jets.They always occurred later than the jets but had dark EUV counterparts appearing in the bright jets.These surge activities were closely associated with two emerging bipoles and their driven flux cancellations at the base region,and were consistent with the magnetic reconnection surge model.
- 【网络出版投稿人】 中国科学院研究生院(云南天文台) 【网络出版年期】2009年 02期
- 【分类号】P182.41
- 【下载频次】130