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Migration of solar polar crown filaments in the past 100 years

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dc.contributor.author Xu, Yan
dc.contributor.author Banerjee, D
dc.contributor.author Chatterjee, Subhamoy
dc.contributor.author Potzi, Werner
dc.contributor.author Wang, Ziran
dc.contributor.author Ruan, Xindi
dc.contributor.author Jing, Ju
dc.contributor.author Wang, Haimin
dc.date.accessioned 2021-06-25T12:44:12Z
dc.date.available 2021-06-25T12:44:12Z
dc.date.issued 2021-03-01
dc.identifier.citation The Astrophysical Journal, Vol. 909, No. 1, 86 en_US
dc.identifier.issn 1538-4357
dc.identifier.uri http://hdl.handle.net/2248/7690
dc.description Restricted Access en_US
dc.description.abstract Polar crown filaments (PCFs) are formed above the polarity inversion line, which separates unipolar polar fields and the nearest dispersed fields. They are important features in studying solar polar fields and their cyclical variations. Due to the relatively weak field strength and projection effects, measuring polar magnetic fields is more difficult than obtaining the field strengths concentrated in active regions at lower latitudes. "Rush-to-the-pole" of PCFs represent the progress of unipolar polar fields from the previous solar cycle being canceled by the dispersed fields generated in the current cycle. Such progress is a good indicator of the polarity reversal in the polar areas and a precursor for the solar maximum. In this study, PCFs are identified from a 100 yr archive, covering cycles 16–24. This archive consists of full-disk Hα images obtained from the Kodaikanal Solar Observatory of the Indian Institute of Astrophysics, Kanzelhöhe Solar Observatory, and Big Bear Solar Observatory. The poleward migration speeds are measured and show an obvious asymmetry in the northern and southern hemispheres. In addition, our results show that the PCFs usually reach their highest latitudes first in the northern hemisphere, except cycle 17. Similarly, previous studies show that the magnetic field reversed first at the north pole in six out of nine cycles. We also compare the temporal variations of PCF migration and the latitude gradient factor of the differential rotation, which shows a trend in the southern hemisphere. Moreover, the migration speed of PCFs does not seem to be well correlated with the maximum sunspot numbers. en_US
dc.language.iso en en_US
dc.publisher IOP Publishing en_US
dc.relation.uri https://doi.org/10.3847/1538-4357/abdc1e
dc.rights © The American Astronomical Society
dc.subject Solar filaments en_US
dc.subject Solar magnetic fields en_US
dc.subject Solar evolution en_US
dc.title Migration of solar polar crown filaments in the past 100 years en_US
dc.type Article en_US


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