The Association of Filaments, Polarity Inversion Lines, and Coronal Hole Properties with the Sunspot Cycle: An Analysis of the McIntosh Database

Abstract

Filaments and coronal holes, two principal features observed in the solar corona are sources of space weather variations. Filament formation is closely associated with polarity inversion lines (PIL) on the solar photosphere which separate positive and negative polarities of the surface magnetic field. The origin of coronal holes is governed by largescale unipolar magnetic patches on the photosphere from where open magnetic field lines extend to the heliosphere. We study properties of filaments, PILs and coronal holes in solar cycles 20, 21, 22 and 23 utilizing the McIntosh archive. We detect a prominent cyclic behavior of filament length, PIL length, and coronal hole area with significant correspondence with the solar magnetic cycle. The spatio-temporal evolution of the geometric centers of filaments shows a butterfly-like structure and distinguishable pole-ward migration of long filaments during cycle maxima. We identify this rush to the poles of filaments to be co-temporal with the initiation of polar field reversal as gleaned from Mount Wilson and Wilcox Solar Observatory polar field observations and quantitatively establish their temporal correspondence. We analyze the filament tilt angle distribution to constrain their possible origins. Majority of the filaments exhibit negative and positive tilt angles in the northern and the southern hemispheres, respectively -strongly suggesting that their formation is governed by the overall large-scale magnetic field distribution on the solar photosphere and not by the small-scale intra-active region magnetic field configurations. We also investigate the hemispheric asymmetry in filaments, PILs, and coronal holes. We find that the hemispheric asymmetry in filaments and PILs are positively correlated -whereas coronal hole asymmetry is uncorrelated -with sunspot area asymmetry.

Properties of filaments in solar cycle 20-23 from McIntosh Archive

“…A bimodal nature in latitudinal distribution of filaments is observed (Hao et al, 2015;Mazumder et al, 2018). Tlatov et al (2016), Chatterjee et al (2017), Hao et al (2015), and Mazumder et al (2018) have reported a butterfly structure in the temporal variation of the latitudinal distribution of filaments. The butterfly diagram is similar to that of sunspot except that the spread in latitude is broader in case of filaments.…”

“…The variation of filament number is found to be cyclic in close proximity to sunspot number variation (Hao et al, 2015;Li et al, 2010). The total filament length in the Carrington map is also found to vary cyclically with time (Tlatov et al, 2016;Mazumder et al, 2018). Mazumder et al (2018) further classified the filaments as associated and unassociated to solar activity belt according to their position inside or outside the sunspot activity belt respectively.…”

“…The total filament length in the Carrington map is also found to vary cyclically with time (Tlatov et al, 2016;Mazumder et al, 2018). Mazumder et al (2018) further classified the filaments as associated and unassociated to solar activity belt according to their position inside or outside the sunspot activity belt respectively. They have found the variation in total length of the filaments is correlated with variation in sunspot area.…”

“…Average tilt angle of filaments are found to decrease from the equator towards the pole for both positive tilt and negative tilt (Tlatov et al, 2016;Mazumder et al, 2018) which is consistent with famous Joy's law of sunspot pair (Hale et al, 1919). The tilt angle of filament was observed to be negative in the northern hemisphere and positive in the southern hemisphere for different length and sunspot belt association criteria by Mazumder et al (2018). Following this observation, they concluded that the origin of most of the filaments are from large-scale magnetic field structure and not from the active region (AR).…”

24 synoptic maps of average magnetic field in 296 prominences measured by the Hanle effect during the ascending phase of solar cycle 21

“…2. The differential rotation effect could in addition explain the north-south symmetry and oblique orientation of the long-axis directions of a prominence, as observed and depicted by Mazumder et al (2018) in their Fig. 6, even if the long-axis direction of the prominence coincides with the direction of the photospheric neutral line, which is not the direction of the distorted north-south magnetic field.…”