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arXiv 2001.01250astro-ph.SR
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两个C级耀斑增强的纵向暗条振荡

Longitudinal filament oscillations enhanced by two C-class flares

Q. M. Zhang, J. H. Guo, K. V. Tam, A. A. Xu

摘要:

本文报道了2010年10月18日在活动区(AR)11112中对一条极长暗条的多波长观测。花丝由两部分组成,东部(EP)和西部(WP)。我们专注于纵向振荡的EP,这是加强了两个同源的C类耀斑在同一AR。C1.3耀斑在没有CME的情况下被限制。灯丝的EP和WP都受到轻微干扰,并在耀斑中幸存下来。5小时后,WP爆发产生了C2.6耀斑和一个狭窄的喷流状CME。在EP中明显识别出三条振荡线(thd $_a$,thd $_b$,thd $_c$),它们的振荡被两个耀斑自然地分为三个阶段。初始振幅范围为1.6 ~ 30 μ m,平均值为$\sim$ 14 μ m,周期范围为34 ~ 73分钟,平均值为$\sim$ 53分钟。磁倾角的曲率半径估计为29至133 μ m,平均值为$\sim$ 74 μ m。阻尼时间范围为$\sim$ 62至$\sim$ 96分钟,平均值为$\sim$ 82分钟。$τ/P$的值介于1.2和1.8之间。对于EP中的$_a$,两次耀斑的振幅在C1.3耀斑后从6.1 μ m增加到6.8 μ m,在C2.6耀斑后进一步增加到21.4 μ m。耀斑扰动引起的周期变化在20%以内。C2.6耀斑后衰减加快。据我们所知,这是第一次报告的大振幅,纵向暗条振荡增强耀斑。数值模拟很好地再现了$_a$的振荡。模拟的振幅和周期与观测值接近,但最后阶段的阻尼时间较长,这意味着除了辐射损失外,还应考虑其他机制。

英文摘要:

In this paper, we report the multiwavelength observations of a very long filament in active region (AR) 11112 on 2010 October 18. The filament was composed of two parts, the eastern part (EP) and western part (WP). We focus on longitudinal oscillations of the EP, which were enhanced by two homologous C-class flares in the same AR. The C1.3 flare was confined without a CME. Both EP and WP of the filament were slightly disturbed and survived the flare. After 5 hrs, eruption of the WP generated a C2.6 flare and a narrow, jet-like CME. Three oscillating threads (thd$_a$, thd$_b$, thd$_c$) are obviously identified in the EP and their oscillations are naturally divided into three phases by the two flares. The initial amplitude ranges from 1.6 to 30 Mm with a mean value of $\sim$14 Mm. The period ranges from 34 to 73 minutes with a mean value of $\sim$53 minutes. The curvature radii of the magnetic dips are estimated to be 29 to 133 Mm with a mean value of $\sim$74 Mm. The damping times ranges from $\sim$62 to $\sim$96 minutes with a mean value of $\sim$82 minutes. The value of $τ/P$ is between 1.2 and 1.8. For thd$_a$ in the EP, the amplitudes were enhanced by the two flares from 6.1 Mm to 6.8 Mm after the C1.3 flare and further to 21.4 Mm after the C2.6 flare. The period variation as a result of perturbation from the flares was within 20\%. The attenuation became faster after the C2.6 flare. To the best of our knowledge, this is the first report of large-amplitude, longitudinal filament oscillations enhanced by flares. Numerical simulations reproduce the oscillations of thd$_a$ very well. The simulated amplitudes and periods are close to the observed values, while the damping time in the last phase is longer, implying additional mechanisms should be taken into account apart from radiative loss.

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