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    Please use this identifier to cite or link to this item: http://ir.lib.ncu.edu.tw/handle/987654321/71387

    Title: 磁雲結構與其起始區域之多點觀測分析;Multipoint Study of Magnetic Cloud Structures and the Associated Solar Origins
    Authors: 林沛萱;Lin,Pei-Hsuan
    Contributors: 太空科學研究所
    Keywords: 太陽;日冕物質拋射;行星際日冕物質拋射;磁雲;太陽風;多點觀測;Solar;Coronal mass ejections;Interplanetary coronal mass ejections;Magnetic cloud;Solar wind;Multipoint observations
    Date: 2016-07-12
    Issue Date: 2016-10-13 12:55:10 (UTC+8)
    Publisher: 國立中央大學
    Abstract: 磁雲為行星際日冕物質拋射的其中之一子集,是在行星際空間中傳播的重要大尺度結構。本篇論文使用了STEREO及Wind太空船的限地太陽風觀測資料,分析六組具有磁管束磁場結構的磁雲事件,並且試圖闡釋觀測資料與理論模型的差異。研究中的每組磁雲事件均涵蓋至少兩艘的太空船觀測資料,並利用線性無力場磁管束擬合法求得各觀測點之磁管束參數。另外,我們也利用STEREO/COR1、COR2及SOHO/LASCO C2的日冕儀影像、STEREO/EUVI及SOHO/EIT的多波段太陽影像、SOHO/MDI的太陽光球層視線方向磁場資料,以及地面BBSO觀測站所提供的Hα波段觀測影像,觀察這六組磁雲事件之太陽起始區域的活動情形。我們的多點磁雲觀測結果顯示,同一個磁雲不同位置的軸向磁場強度的差異並不大,但磁管束半徑並不相同,各觀測點的磁場螺旋特性都與太陽起始區域相同,且由磁雲磁管束中心軸軸向姿態的分布情形可以發現,磁雲在軸向的空間分布尺度最大可至0.8 AU,以上性質均符合傳統大尺度磁雲模型所預測的圖像。但是當磁雲的磁場結構受到其他太陽風物質影響而變形時,便會造成磁管束擬合結果的誤差。分析的六組事件中,有一半的事件所對應之太陽表面起源區域並無明顯的太陽活動現象,代表1 AU附近所觀測到的磁雲尺度與太陽爆發現象的劇烈程度可能並無直接關連。;Magnetic cloud (MC) is one subset of the interplanetary coronal mass ejection (ICME), which is an important large-scale structure in the interplanetary space. In this study, we use the in-situ solar wind data provided by STEREO and Wind spacecrafts to analyze the properties and global configurations of six MC events. We attempt to clarify the difference between the classical large-scale flux rope model and observations. Each analyzed event has complete data coverage measured by at least two spacecrafts. The flux rope parameters of MCs are derived from a linear force-free field fitting. In addition, we identify the associated solar origins based on coronagraph images from STEREO/COR1&2 and SOHO/LASCO C2, multi-wavelength images from STEREO/EUVI and SOHO/EIT, photospheric line-of-sight magnetograms from SOHO/MDI, and ground based Hα images from BBSO. Our results show that the flux rope radius could be quite different but the central axial magnetic field strength would be similar at different locations of a MC. Magnetic helicity sign of a MC is found to remain invariant from the solar source region to the interplanetary space. It is also found that the scale of a MC in the axial direction can extend to 0.8 AU. All the above properties can be explained by the classical large-scale MC flux rope model. Note that the distorted flux rope magnetic fields due to the interaction with other solar wind structures would affect the fitting results. Half of the studied MC events do not have the strong solar explosions, which implies that the MCs at 1 AU may have weak correspondence with the magnitude of solar activity in source regions.
    Appears in Collections:[太空科學研究所 ] 博碩士論文

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