Abstract Details

Name: Pooja Devi
Affiliation: Kumaun University
Conference ID: ASI2021_443
Title : Variation of chromospheric features as a function of latitude and time using Ca-K spectroheliograms for solar cycles 15 – 23
Authors and Co-Authors : Pooja Devi(1), Jagdev Singh(2), Ramesh Chandra(1), Priyal Muthu(2), Reetika Joshi(1) (1) Department of Physics, DSB Campus, Kumaun University, Nainital 263001, India (2) Indian Institute of Astrophysics, Bangalore- 560 0034, India
Abstract Type : Oral
Abstract Category : Sun and the Solar System
Abstract : We analyse the Ca-K images obtained at Kodaikanal Observatory as a function of latitude and time for the period of 1913 – 2004 covering the solar cycle number 15 to 23. We classify the chromospheric activity as plage, Enhanced Network (EN), Active Network (AN), and Quiet Network (QN) areas to differentiate between large strong active and small weak active regions. The plage areas are found to follow the ~11-year solar cycle up to 50 deg latitude belt. This variation is also shown by weak activity represented by EN, AN and QN with significant amplitude up to about 50 deg latitude in both the hemispheres. The amplitude of variation is minimum around 50 deg latitude and again increases by small amount in the polar region. In addition, the plots of Plages, EN, AN and QN as a function of time indicate the maximum of activity at different latitude occur at different epoch. The cross-correlation coefficients are computed to see the phase difference between the variations at different latitudes with that of 30-40 deg latitude belt. The activity is found to be shifted from mid-latitude belts towards the equatorial belts at fast speed at the beginning of solar cycle and at slower speed as the cycle progresses. This speed is found to vary from ~19 to 3 m/s considering all the data for the observed period. This speed can be linked with speed of meridional flows those believed to occur between convection zone and the surface of the Sun.