Motion and Magnetic Flux Changes of Coronal Bright Points Relative to Supergranular Cell Boundaries

Autor: R. Attie, Nasibe Alipour, M. Yousefzadeh, Hossein Safari
Rok vydání: 2015
Předmět:
Zdroj: Solar Physics. 291:29-39
ISSN: 1573-093X
0038-0938
DOI: 10.1007/s11207-015-0809-6
Popis: To calculate the magnetic flux and the horizontal movement of coronal bright points (CBPs) in relation to supergranular cell boundaries, the time series of the SDO/HMI visible-light continuum images and SDO/AIA EUV images for 13 February 2011 have been studied. The supergranular lanes were detected in HMI continuum images using the automatic supergranular cell recognition method. The automatic identification and tracking method was applied for detecting the CBPs in AIA 193 A images. By applying the ball-tracking method on HMI continuum images, the underlying flow fields were determined. By using the velocity fields and the automatic supergranular cell recognition method, the lanes and boundaries were detected. The locations of CBPs were projected on the photospheric co-spatial and co-temporal images. We found that about 90 % of the locations of CBPs correspond to the lane of the supergranular cell boundaries (network CBPs or NCBPs) of which about 40 % of them appeared at junctions. The remaining 10 % appeared within the supergranular regions (internetwork CBPs or INCBPs). The horizontal velocities for NCBPs and INCBPs were about $1.6\pm0.1~\mbox{km}\,\mbox{s}^{-1}$ and $1.7\pm0.1~\mbox{km}\,\mbox{s}^{-1}$ , respectively. Using the magnetic field extrapolation, we were able to detect the bipoles underlying CBPs, and we studied their magnetic evolution. The orientation of CBPs observed in the 171, 193, and 211 A images and the orientation of their magnetic bipoles are positively correlated. For out of 50 INCBPs, 54 % showed cancellation, 32 % emergence, and 12 % complex flux changes. Out of 90 NCBPs, 60 % presented cancellation, 20 % showed emergence, and 20 % showed complex flux changes.
Databáze: OpenAIRE
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