Long term study of the solar filaments from the Synoptic Maps as derived from $H_{\alpha }$ Spectroheliograms of Kodaikanal Observatory

Abstract

The century long (1914-2007) $H_{\alpha }$ (656.28 nm) spectroheliograms from Kodaikanal Solar Observatory (KSO) have been recently digitised. Using these newly calibrated, processed images we study the evolution of dark elongated on disk structures called filaments, potential representatives of magnetic activities on the Sun. To our knowledge this is the oldest uniform digitised dataset with daily images available today in $H_{\alpha }$. We generate Carrington maps for entire time duration and try to find the correspondences with maps of same rotation from Ca II K KSO data. Filaments are segmented from Carrington maps using a semi-automated technique and are studied individually to extract their centroids and tilts. We plot the time-latitude distribution of filament centroids producing Butterfly diagram, which clearly shows presence of poleward migration. We separate polar filaments for each cycle and try to estimate the delay between the polar filament number cycle and sunspot number cycle peaks. We correlate this delay with the same between polar reversal and sunspot number maxima. This provides new insight on the role of polar filaments on polar reversal.

arXiv comment24 pages, 9 figures, submitted to ApJ

References in corpus (7)

• Observation and Simulation of Longitudinal Oscillations of an Active Region Prominence
• SOHO/SUMER Observations of Prominence Oscillation Before Eruption
• Statistical Analysis of Filament Features Based on the Hα Solar Images from 1988 to 2013 by Computer Automated Detection Method
• Butterfly Diagram and Carrington Maps for Century-Long Ca II K Spectroheliograms from Kodaikanal Observatory
• Causal Relationships between Eruptive Prominences and Coronal Mass Ejections
• Tilt Angles of Solar Filaments over the Period 1919-2014
• Latitude migration of solar filaments

Cited by in corpus (10)

• Full-disc Ca II K observations -- a window to past solar magnetism
• The Association of Filaments, Polarity Inversion Lines, and Coronal Hole Properties with the Sunspot Cycle: An Analysis of the McIntosh Database
• Long-Term Evolution of the Sun's magnetic field during Cycles 15--19 based on their proxies from Kodaikanal Solar Observatory
• Collective Study of Polar Crown Filaments in the Past Four Solar Cycles
• Time-Latitude Distribution of Prominences for 10 Solar Cycles: A study using Kodaikanal, Meudon and Kanzelhohe Data
• Chromospheric Synoptic Maps of Polar Crown Filaments
• Analysis of full-disc H alpha observations: Carrington maps and filament properties in 1909-2022
• Solar Cycle Evolution of Filaments over a Century: Investigations with the Meudon and McIntosh Hand-drawn Archives
• A New Comprehensive Data Set of Solar Filaments of 100 yr Interval. I
• Detection of Solar Filaments using Suncharts from Kodaikanal Solar Observatory Archive Employing a Clustering Approach