The impact of aging on the rotation rate of calcium plages in the years 1967–1977 |
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| Authors: | Maurizio Ternullo |
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| Institution: | (1) Osservatorio Astrofisico di Catania, CNR - Gruppo Nazionale di Astronomia, U.d.R. di Catania, Citta' Universitaria, v. le A. Doria, I-95125 Catania, Italy |
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| Abstract: | An analysis of Ca ii spectroheliograms obtained at Catania Astrophysical Observatory throughout the years 1967–1977 has been carried out, to throw light on the complex relationship linking (Ternullo, 1986) the angular rotation rate of Ca plages with their age, as well as with solar cycle phase, and with latitude. Given the rotation law w =, a + b sin2
I, solar-cycle-related oscillatory properties both of a and b coefficients are described, both for young and old Ca plages.The aging-dependent rate-increments vary, for each epoch, both in module and sign with latitude; that results in deep distortions of the differential rotation latitudinal profile, which exhibits, when old plages are taken into account, a fine structure (Ternullo, 1987). Such a fine structure is absent in the young plage differential rotation profile.Throughout the time interval under examination, the torsional waves observed by Howard and LaBonte (1980) have appeared to be in close spatial relationship with the latitude bands where aging-dependent rate increments occur.
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