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arXiv 1306.3393astro-ph.SR
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与出现的小尺度磁环有关的安静太阳色球层活动的证据

Evidence of quiet Sun chromospheric activity related to an emerging small-scale magnetic loop

P. Gömöry, H. Balthasar, K. G. Puschmann

摘要:

目的:研究平静太阳大气中靠近盘中心的磁通量出现的时间演化。研究方法:我们结合高分辨率的SoHO/MDI磁图与TRACE观测在1216年的通道,以分析一个新兴的小规模的磁环的时间演变和它的痕迹在色球层。结果:首先,我们发现磁通出现的信号非常接近位于盘中心的超颗粒网络边界的边缘。新出现的磁通量首先以不对称双极元素的形式出现在MDI磁图中,即具有负极性的贴片比具有相反极性的相应贴片弱大约两倍。磁通量和磁通量密度的平均值分别达到1.6 x 10^18 Mx、-8.5 x 10^17 Mx和55 Mx cm^-2、-30 Mx cm^-2。出现的功能相反极性补丁之间的空间距离增加约2.5”至5.0”的循环,这是不超过36分钟的寿命期间。一个更精确的寿命估计的功能是不可能的,因为在MDI磁图的时间序列的间隙。色球层对磁偶极子的响应比光球磁图晚9分钟左右。它由一个准周期性的时间局部增亮序列组成,在1216年12月TRACE通道中可见,持续约14分钟,与连接两个相反磁极的轴共空间。结论:我们确定所观察到的事件作为一个小规模的磁回路出现在光球层,随后上升到色球层。我们讨论的可能性,在色球发射检测到的波动可能反映磁场振荡传播到色球的波的形式。

英文摘要:

Aims: We investigate the temporal evolution of magnetic flux emergence in the quiet Sun atmosphere close to disk center. Methods: We combine high-resolution SoHO/MDI magnetograms with TRACE observations taken in the 1216 Å channel in order to analyze the temporal evolution of an emerging small-scale magnetic loop and its traces in the chromosphere. Results: At first place, we find signatures of flux emergence very close to the edge of a supergranular network boundary located at disk center. The new emerging flux appears first in the MDI magnetograms in form of an asymmetric bipolar element, i.e. the patch with negative polarity is roughly two-times weaker than the corresponding patch with opposite polarity. The average values of magnetic flux and magnetic flux densities reach 1.6 x 10^18 Mx, -8.5 x 10^17 Mx, and 55 Mx cm^-2, -30 Mx cm^-2, respectively. The spatial distance between the opposite polarity patches of the emerged feature increases from about 2.5" to 5.0" during the lifetime of the loop which was not longer than 36 min. A more precise lifetime-estimate of the feature was not possible because of a gap in the temporal sequence of the MDI magnetograms. The chromospheric response to the emerged magnetic dipole occurs ~ 9 minutes later with respect to the photospheric magnetograms. It consists of a quasi-periodic sequence of time-localized brightenings visible in the 1216 Å TRACE channel apparent for ~ 14 minutes and being co-spatial with the axis connecting the two patches of opposite magnetic polarity. Conclusions: We identify the observed event as a small-scale magnetic loop emerging at photospheric layers and subsequently rising up to the chromosphere. We discuss the possibility that the fluctuations detected in the chromospheric emission probably reflect magnetic field oscillations which propagate to the chromosphere in form of waves.

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