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Title: Abnormal rotation rates of sunspots and durations of associated flares
Authors: Suryanarayana, G. S
Hiremath, K. M
Bagare, S. P
Hegde, M
Keywords: Sunspots – sun;Rotation – sun;Flares
Issue Date: Aug-2015
Publisher: EDP Sciences
Citation: Astronomy & Astrophysics, Vol. 580, A25
Abstract: Context. Short-duration and long-duration flares are important in terms of their association with coronal heating and coronal mass ejections, respectively. Sunspot motions in the photosphere have been known to be associated with flare occurrences. Aims. We study the association between the abnormal rotation rates (longitudinal displacement in a given latitude in contrast with the rotation of spots around their umbral centre) of sunspots and flare duration. Methods. We compute the rotation rates of sunspots for different days during their evolution. We consider rotation rates that are in excess of one standard deviation as abnormal rotation rates. Also, the duration of time between the initial and final stages of the flares are computed. Results. Using Kodaikanal Observatory white light picture and GOES soft X-ray flare data, we find that a good association with a high significance exists between abnormal rotation rates of sunspots and flare durations. In contrast, we find that duration of flare is independent of sunspot area. Conclusions. The present study suggests that sub-surface dynamics plays a dominant role in determining the duration and rate of dissipation of energy during flares.
Description: Open Access
ISSN: 0004-6361
Appears in Collections:IIAP Publications

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