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Variations in Ca-K line profiles and Ca-K line features as a function of latitude and solar cycle during the 20th century

Published online by Cambridge University Press:  27 November 2018

Jagdev Singh ,
M. Priyal ,
G. Sindhuja  and
B. Ravindra
Jagdev Singh
Affiliation:
Indian Institute of Astrophysics, Bengaluru-560 034 email: [email protected]
M. Priyal
Affiliation:
Bharathiyar University, Coimbatore, India-641046 email: [email protected]
G. Sindhuja
Affiliation:
Udaipur Solar Observatory, Udaipur, Rajasthan, India email:[email protected]
B. Ravindra
Affiliation:
Indian Institute of Astrophysics, Bengaluru-560 034 email: [email protected]
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Abstract

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The analysis of the Ca-K line spectra as a function of latitude and integrated over the visible disk obtained during the period of 1989–2011 at the Kodaikanal Solar Tower Telescope shows that the FWHM of the K1 distribution at different latitudes varies by negligible amount at about 60° latitude whereas it varies significantly at other latitudes. Findings, especially the fewer variations in mid-latitude belts as compared to polar regions and complex variation in the shift in the activity around 60° latitude belt, will have important implications on the modeling of solar dynamos. Further, we have generated a uniform set of digitized Ca-K line images by selecting images considering the intensity distribution of the images corrected for the instrumental vignetting for the data obtained at Kodaikanal during the 20th century. Then, we have determined the percentage of plage and network areas by using the intensity and area threshold values.

Type
Contributed Papers
Information
Proceedings of the International Astronomical Union , Volume 13 , Symposium S340: Long-term Datasets for the Understanding of Solar and Stellar Magnetic Cycles , February 2018 , pp. 23 - 26
Copyright
Copyright © International Astronomical Union 2018 

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