Differential Rotation of the Solar Chromosphere: A Century-long Perspective from Kodaikanal Solar Observatory Ca II K Data

• DOI: 10.48550/arxiv.2311.18800
• Publication Date: 2023-01-01
• Authors: Dibya Kirti Mishra; S. Routh; Bibhuti Kumar Jha; Theodosios Chatzi...; Judhajeet Basu; Subhamoy Chatterjee; Dipankar Banerjee; I. Ermolli
• Keywords: Chromosphere; Sunspot; Photosphere; Solar rotation

Chromospheric differential rotation is a key component in comprehending the atmospheric coupling between chromosphere and photosphere at different phases of solar cycle. In this study, we therefore utilize newly calibrated multidecadal Ca II K spectroheliograms (1907-2007) from Kodaikanal Solar Observatory (KoSO) to investigate using technique image cross-correlation. Our analysis yields chromospheric rate $\Omega (\theta) = (14.61\pm 0.04 - 2.18\pm 0.37\sin^2{\theta} 1.10 \pm 0.61\sin^4{\theta})^\circ{\rm /day}$. These results suggest plages exhibit an equatorial 1.59% faster than when compared with measured sunspots also smaller latitudinal gradient same. To compare our those other observatories, have applied method on small sample data Rome, Meudon, Mt. Wilson which support findings KoSO data. Additionally, not found any significant north-south asymmetry or systematic variation over last century.