A butterfly diagram and carrington maps for century-long Ca II K spectroheliograms from the Kodaikanal observatory
Journal Article
·
· Astrophysical Journal
The 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 arcmin{sup 2} 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.
- OSTI ID:
- 22869141
- Journal Information:
- Astrophysical Journal, Journal Name: Astrophysical Journal Journal Issue: 1 Vol. 827; ISSN ASJOAB; ISSN 0004-637X
- Country of Publication:
- United States
- Language:
- English
Similar Records
Long-term Study of the Solar Filaments from the Synoptic Maps as Derived from H{sub α} Spectroheliograms of the Kodaikanal Observatory
Association of Plages with Sunspots: A Multi-Wavelength Study Using Kodaikanal Ca ii K and Greenwich Sunspot Area Data
Variation of Supergranule Parameters with Solar Cycles: Results from Century-long Kodaikanal Digitized Ca ii K Data
Journal Article
·
Wed Nov 01 00:00:00 EDT 2017
· Astrophysical Journal
·
OSTI ID:22875646
Association of Plages with Sunspots: A Multi-Wavelength Study Using Kodaikanal Ca ii K and Greenwich Sunspot Area Data
Journal Article
·
Tue Jan 31 23:00:00 EST 2017
· Astrophysical Journal
·
OSTI ID:22663955
Variation of Supergranule Parameters with Solar Cycles: Results from Century-long Kodaikanal Digitized Ca ii K Data
Journal Article
·
Thu Jun 01 00:00:00 EDT 2017
· Astrophysical Journal
·
OSTI ID:22663569