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与微暗条爆发相关的太阳小尺度活动
Alternative TitleSolar small-scale activity associated with minifilament eruption
洪俊超
Subtype博士
Thesis Advisor姜云春
2014-05-26
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爆发 微暗条 喷流 日冕亮点
Abstract太阳小尺度活动普遍发生在太阳大气中,主宰了宁静区和冕洞区的动力学 演化。随着地面和空间太阳观测仪器的分辨率提升,太阳物理观测研究向着更 小尺度和更精细结构的方向发展。本论文主要通过空间卫星SDO和STEREO组 成的多视角、多波段全日面观测研究了几个与微暗条爆发相关的小尺度活动。 本论文的研究内容如下: 2010年7月19日,一个极紫外微暗条通道在日面中心附近爆发。其形成至 爆发的整个过程都被具有高时空分辨率SDO所观测。它的爆发过程同时也被另 一颗卫星STEREO-A从太阳东部边缘观测到。SDO的日面观测清楚地显示了微 暗条的形成与爆发在诸多方面类似于大尺度暗条,例如相反极性的光球磁场的 剪切运动,汇聚运动以及对消,还有耀斑增亮、日冕暗化和爆发后环的出现。 在STEREO-A的视场内该事件却表现为一个小的EUV喷流,并随后在日冕仪观 测中产生一个窄CME即白光喷流。从而该事件被认定为一次极紫外爆裂喷流, 并且是极紫外爆裂喷流产生微CME的首例观测。 通过分析SDO和STEREO-A的多角度观测,一个极区解缠喷流被认证为起 源于一个小日珥爆发的EUV爆裂喷流。SDO的视角中,这个小喷流在304埃上 展示出解缠行为,在171埃上表现为两个喷流脊的出现。通过跟踪喷流中一个 螺旋上升的亮结构,我发现该喷流以旋转速度0.76度每秒、周期475秒作横向解缠 运动,向上喷射的速度约108千米每秒。考虑到该爆裂喷流持续解缠近7分钟,我 同时估计出其纽缠为0.89圈。STEREO的观测进一步表明该爆裂喷流实际上是 一个鞭子状的日珥爆发,并且产生了一个白光喷流。爆裂喷流与微CME的联系 已经被诸多观测报道。所以有必要去调查爆裂喷流与微CME事件的普遍关系。 日冕亮点是一类尺度小、可以长期存在的日冕增亮,他们在宁静区和冕洞 中几乎无处不在。利用高时空分辨率SDO/AIA、HMI观测数据,我从日面上 的一个冕洞中选取了30个演化寿命分布在5-35小时内的日冕亮点,研究它们的 爆发行为。其中大约有四分之一至三分之一的CBPs在其一生的演化当中会经 历一次或多次微暗条爆发。这些暗条爆发对应亮点脉冲增亮,与亮点下的磁偶 极子的汇聚对消密切相关。这也是首次发现日冕亮点与微暗条的形成爆发有 关。这些新的观测结果同时也暗示着日冕亮点在动力学演化和磁结构上要比先 前所认为的复杂的多。 2011年4月22日,利用SDO/AIA、HMI的观测以及辅助观测STEREO/EUVI, 我分析了一个宁静区中的小尺度喷流。通过磁图和计算出来的光球水平流动, 我发现该喷流发生在一个超米粒元胞边界,与单极网络场和网络内浮现偶极子 的相互作用息息相关。AIA极紫外像中,该喷流实际上涉及两次沿不同方向的 等离子喷射。第一次喷流沿着一个扭曲的路径被引导进入附近一个可能的小暗 条通道,而第二次喷流则沿着另外一个方向径直射出去,该方向与外推出去的 势场方向一致。根据这些观测,我认为在喷流爆发过程中,新浮现的磁场在超 米粒边界与不同高度的外界单极场发生磁重联,从低到高分别是磁篷(magnetic canopy)和大的磁环(high-reaching loops),从而使得两次等离子喷流沿着不同 的方向。该喷流的观测结果也表明了宁静区低处磁场的非势性和高层磁场的势 场特征。 以上的研究结果表明无论是喷流还是日冕亮点都可能涉及到微暗条爆。前 两者是日面上无处不在的日冕加热贡献物,因此,微尺度暗条结构可能普遍存 在太阳底层大气,微暗条爆发向日冕输送物质、能量、磁螺度可能具有普遍意 义。高分辨率的观测关于进一步理解微暗条的形成、精细结构和磁场情况将是 十分必要的。
Other AbstractSolar small-scale activities are ubiquitous over quiet-Sun region and coronal hole. Smaller eruptive events and finer structures are studied because of the development of solar observation from both ground-based and space-borne instruments. By means of multi-angle and multi-wavelength observations from SDO and STEREO spacecraft, this thesis focuses on kinds of small-scale activities associated with minifilament eruptions. The so-called mini coronal mass ejections (CMEs) were recently identified as small-scale eruptive events showing the same on-disk characteristics as largescale CMEs, and Moore et al. 2010 further found that one-third of polar X-ray jets are the so-called blowout jets, in which the jet-base magnetic arch, often carrying a filament, undergoes a miniature version of the blowout eruptions that produce major CMEs. By means of the two viewpoint observations from SDO and STEREO-A, I present the first observations that a blowout jet from the eruption of an EUV mini-filament channel in the quiet Sun was indeed associated with a real micro-CME. Captured by the on-disk SDO observations, the whole life of the mini-filament channel, from the formation to eruption, was associated with convergences and cancellations of opposite-polarity magnetic flux in the photosphere, and its eruption was accompanied by a small flare-like brightening, a small corona dimming, and posteruptive loops. The near-limb counterpart of the eruption observed by STEREO-A, however, showed up as a small EUV jet followed by a white-light jet. These observations not only confirm the previous results that mini-filaments have characteristics common to large-scale ones, but also give clear evidences that blowout jets can result from the eruptions of minifilaments and are associated with mini-CME. It is well known that some coronal jets exhibit helical structures and untwisting. I attempt to inspect the origin of twist in a blowout jet. By analyzing observations with multiple viewpoints from SDO and STEREO-A, a polar untwisting jet is identified as a blowout EUV jet that comes from the eruption of a prominence. In the SDO views, the small jet exhibits untwisting behavior in 30.4 nm and two jet-spires in 17.1 nm. By tracking a bright feature moving helically in the jet, I find that the jet untwists itself in a period of 475 s with a rotational speed of 0.76 degree per second, and is ejected upward at an approximately constant velocity(about 108 km per sec). Considering that the blowout jet untwists in about 7 min, we also estimated thatthe twist completes about 0.89 turns. STEREO observations further suggest that the blowout jet is indeed a whiplike prominence eruption and leads to a white-light jet. Blowout jets associated with micro CMEs have already been reported in several observations It is necessary to inspect a general relationship between blowout jets and micro-CME events. Coronal bright points (CBPs) are small-scale, long-lived coronal brightenings that always correspond to photospheric network magnetic features of opposite polarity. I adopt 30 bright points with lifetime ranging from 5 h to 35 h in a coronal hole on solar disk to study their eruptive behavior using data from AIA and HMI onboard SDO. About one quarter to one third of the CBPs in the coronal hole go through miniature filament eruptions one or more throughout their lifetime. The filament eruptions occur in temporal association with the brightness maxima of CBPs and are strong related to convergence and cancelation of underlying magnetic dipoles. These new observations also indicate that CBPs are more complex in dynamical evolution and magnetic structure than previously thought. I analyzed a small-scale jet observed on April, 22, 2011 in a solar quiet region, using data from SDO/AIA, HMI, with supplemental data from STEREO/EUVI. From HMI magnetograms and calculated photospheric flows, I find that the jet is related
Subject Area天文学
Pages90
Language中文
Document Type学位论文
Identifierhttp://ir.ynao.ac.cn/handle/114a53/6624
Collection太阳物理研究组
Recommended Citation
GB/T 7714
洪俊超. 与微暗条爆发相关的太阳小尺度活动[D]. 北京. 中国科学院研究生院(云南天文台),2014.
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