CORONAL DYNAMIC ACTIVITIES IN THE DECLINING PHASE OF A SOLAR CYCLE

ABSTRACT It has been known that some solar activity indicators show a double-peak feature in their evolution through a solar cycle, which is not conspicuous in sunspot number. In this Letter, we investigate the high solar dynamic activity in the declining phase of the sunspot cycle by examining the...

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Bibliographic Details
Published in:Astrophysical journal. Letters 2016-12, Vol.833 (1), p.L11-L11
Main Authors: Jang, Minhwan, Woods, T. N., Hong, Sunhak, Choe, G. S.
Format: Article
Language:English
Subjects:
ASTROPHYSICS, COSMOLOGY AND ASTRONOMY
COMPARATIVE EVALUATIONS
Dynamics
EVOLUTION
Fluxes
MAGNETIC FIELDS
MAGNETIC FLUX
MASS
Merging
Solar activity
SOLAR CORONA
SOLAR CYCLE
Solar cycles
Splitting
SUN
Sun: activity
Sun: corona
Sun: coronal mass ejections (CMEs)
Sun: magnetic fields
Sunspot cycle
SUNSPOTS
SURFACES
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Summary:ABSTRACT It has been known that some solar activity indicators show a double-peak feature in their evolution through a solar cycle, which is not conspicuous in sunspot number. In this Letter, we investigate the high solar dynamic activity in the declining phase of the sunspot cycle by examining the evolution of polar and low-latitude coronal hole (CH) areas, splitting and merging events of CHs, and coronal mass ejections (CMEs) detected by SOHO/LASCO C3 in solar cycle 23. Although the total CH area is at its maximum near the sunspot minimum, in which polar CHs prevail, it shows a comparable second maximum in the declining phase of the cycle, in which low-latitude CHs are dominant. The events of CH splitting or merging, which are attributed to surface motions of magnetic fluxes, are also mostly populated in the declining phase of the cycle. The far-reaching C3 CMEs are also overpopulated in the declining phase of the cycle. From these results we suggest that solar dynamic activities due to the horizontal surface motions of magnetic fluxes extend far in the declining phase of the sunspot cycle.
ISSN:2041-8205
2041-8213
DOI:10.3847/2041-8213/833/1/L11