Please use this identifier to cite or link to this item: http://hdl.handle.net/2248/7139
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dc.contributor.authorChatterjee, Subhamoy-
dc.contributor.authorBanerjee, D-
dc.contributor.authorRavindra, B-
dc.date.accessioned2020-11-17T14:19:09Z-
dc.date.available2020-11-17T14:19:09Z-
dc.date.issued2016-08-10-
dc.identifier.citationThe Astrophysical Journal, Vol. 827, No. 1, 87en_US
dc.identifier.issn1538-4357-
dc.identifier.urihttp://prints.iiap.res.in/handle/2248/7139-
dc.descriptionRestricted Access © The American Astronomical Society http://dx.doi.org/10.3847/0004-637X/827/1/87en_US
dc.description.abstractThe century-long (1907–2007) Ca II K spectroheliograms from the Kodaikanal Solar Observatory (KSO) are calibrated, processed, and analyzed to follow the evolution of the bright on-disc structures called plages, possible representatives of magnetic activity on the Sun. This is the longest data set studied in Ca II K to date, covering about 9.5 cycles of 11 yr periods. Plages are segmented with area ≥1 arcmin² using global thresholds for individual full disc images and subsequent application of a morphological closing operation. The plage index is calculated and is seen to have a close positive correlation with the fractional disc area covered by plages. The newly generated plage area cycle (from KSO) was compared with the same from the Mount Wilson Observatory (correlation 95.6%) for the overlapping years, i.e., 1915–2000. This study illustrates the time–latitude distribution of plage centroids by rendering a butterfly diagram (as observed for sunspots). The 3D visualization of the diagram shows one-to-one mapping between plage location, time, and area. This work further delineates the positional correlation between magnetic patches and plage regions through the comparison of synoptic maps derived from both KSO Ca II K images and space-based full disc line-of-sight magnetograms. Regular synoptic magnetograms from ground-based observatories are available only after 1970s. Thus the long term Ca II K data from KSO can be used as a proxy for estimating magnetic activity locations and their strengths at earlier times.en_US
dc.language.isoenen_US
dc.publisherIOP Publishingen_US
dc.subjectAstronomical databases: miscellaneousen_US
dc.subjectMethods: data analysisen_US
dc.subjectSun: chromosphereen_US
dc.subjectSun: faculae, plagesen_US
dc.subjectSun: magnetic fieldsen_US
dc.subjectTechniques: imageen_US
dc.titleA butterfly diagram and carrington maps for century-long Ca II K spectroheliograms from the Kodaikanal Observatoryen_US
dc.typeArticleen_US
Appears in Collections:IIAP Publications



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