使用SDO / AIA觀測閃焰亮帶之運動情形;Elongation and Separation of Flare Ribbons by Using SDO/AIA

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Title:	使用SDO / AIA觀測閃焰亮帶之運動情形;Elongation and Separation of Flare Ribbons by Using SDO/AIA
Authors:	楊昀蓁 Yang, Yun-Chen
Contributors:	國立中央大學
Keywords:	太陽;閃焰;亮帶;solar;flare;ribbon
Date:	2018-07-27
Issue Date:	2018-08-31 12:57:35 (UTC+8)
Abstract:	太陽閃焰是在太陽盤面或邊緣觀測到的突發閃光現象，是太陽表面最為激烈的一種能量釋放過程。閃焰過程中會放射出許多不同波段的射線(從無線電波(radio wave) 到伽瑪射線(γ-ray))，其中軟與硬X 射線(soft/hard X-ray，簡稱S/HXR) 為本論文的研究重點之一。電子在閃焰的過程中被加速，沿著磁場向太陽表面運動並與密度較高的色球層碰撞，經由韌致輻射(bremsstrahlung) 效應放射出HXR。而因此被加熱的色球層電漿由於溫度梯度沿磁場線向上抬升，同時伴隨著SXR 放射。本論文利用Solar Dynamics Observatory (SDO)上搭載的Helioseismic and Magnetic Imager (HMI) 與 Atmospheric Imaging Assembly (AIA) 所提供的視線方向磁場資料以及1600 A 影像，分別觀察閃焰發生時的亮帶運動情形與磁場強度，並估算閃焰中粒子加速機制之一的電場及各項物理參數隨時間之變化。另一方面，我們根據Neupert effect ，以GOES (Geostationary Operational Environmental Satellite) 提供 SXR 資料取時間微分來代表HXR。比較後我們發現多數事件的電場比HXR 還早達到峰值，這顯示電場與電子加速有著密切的關係。另外，多項參數的峰值與HXR 峰值或閃焰規模之間呈現高度的正向關係，這讓我們對閃焰的特性有了更進一步的瞭解。;Solar flares are sudden flash phenomena observed on the solar disk or limb, which are the most powerful energy release event in the solar system. They emit radiation across the entire electromagnetic spectrum, from radio to γ –rays. In the progress of solar flare, electrons are accelerated and move toward to the solar surface along the magnetic field line, bumped into the dense chromosphere and then emit hard X-ray by bremsstrahlung. Because of the temperature gradient, the heated chromospheric plasma rise along the magnetic field line with soft X-ray emission. This study put emphasis on the relation between X-ray emissions and the electric field (one of the particle acceleration mechanisms in solar flare), also other relative parameters. We observe the motion of ribbons with 1600 A images, then combine the line of sight magnetic field data to calculate the time profile of electric field and other relative parameters. These data are provided by Atmospheric Imaging Assembly (AIA) and Helioseismic and Magnetic Imager (HMI) both on Solar Dynamics Observatory (SDO) respectively. On the other hand, according to Neupert effect, we take the time derivative of Soft X-ray flux provided by Geostationary Operational Environmental Satellite (GOES) to stand for hard X-ray flux. By comparing the peak time of hard X-ray and electric field, we found out that electric field peak time prior to that of hard X-ray in most of the events we studied. This indicate close relation between electric field and particle acceleration. Furthermore, high positive correlations between the peak values of several parameters and that of hard X-ray or soft X-ray are found. This also improve our understanding about solar flare properties.
Appears in Collections:	[Graduate Institute of Space Science] Department of Earth Sciences

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