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Examining the optical intensity and magnetic field expansion factor in the open magnetic field regions associated with coronal holes

Published online by Cambridge University Press:  24 September 2020

Chia-Hsien Lin Open the ORCID record for Chia-Hsien Lin [Opens in a new window] ,
Guan-Han Huang  and
Lou-Chuang Lee
Chia-Hsien Lin
Affiliation:
Graduate Institute of Space Science, National Central University, Taiwan email: [email protected]
Guan-Han Huang
Affiliation:
Graduate Institute of Space Science, National Central University, Taiwan email: [email protected]
Lou-Chuang Lee
Affiliation:
Institute of Earth Sciences, Academia Sinica, Taiwan
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Abstract

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Coronal holes can be identified as the darkest regions in EUV or soft X-ray images with predominantly unipolar magnetic fields (LIRs) or as the regions with open magnetic fields (OMF). Our study reveals that only 12% of OMF regions are coincident with LIRs. The aim of this study is to investigate the conditions that affect the EUV intensity of OMF regions. Our results indicate that the EUV intensity and the magnetic field expansion factor of the OMF regions are weakly positively correlated when plotted in logarithmic scale, and that the bright OMF regions are likely to locate inside or next to the regions with closed field lines. We empirically determined a linear relationship between the expansion factor and the EUV intensity. The relationship is demonstrated to improve the consistency from 12% to 23%. The results have been published in Astrophysical Journal (Huang et al. 2019).

Keywords

magnetic fieldsSun: coronaSun: magnetic fieldsmethods: statistical
Type
Contributed Papers
Information
Proceedings of the International Astronomical Union , Volume 15 , Symposium S354: Solar and Stellar Magnetic Fields: Origins and Manifestations , June 2019 , pp. 228 - 231
Copyright
© International Astronomical Union 2020

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