Please use this identifier to cite or link to this item: http://hdl.handle.net/2248/3174
Title: Measurement of Kodaikanal white-light images - IV. Axial Tilt Angles of Sunspot Groups
Authors: Sivaraman, K. R
Gupta, S. S
Howard, R. F
Keywords: Bipolar magnetic regions;East west Inclination;Active regions;Field lines;Sun
Issue Date: Oct-1999
Publisher: Kluwer Academic Publishers
Citation: Solar Physics, Vol. 189, No. 1, pp. 69-83
Abstract: The Kodaikanal sunspot data set, covering the interval 1906-1987, is used in conjunction with the similar Mount Wilson sunspot data set, covering the interval 1917-1985, to examine characteristics of sunspot group axial tilt angles. Good agreement is demonstrated between various results derived from the two independent data sets. In particular, the tendency for sunspot groups near the average tilt angle to be larger than those far from the average tilt angle is confirmed. Similarly the faster residual rotation rate for groups near the average tilt angle is also confirmed. Other confirmations are made for the relationships between latitude drift of sunspot groups and tilt angle, polarity separations, and axial expansion. Evidence is presented that tilt angles averaged over these long time intervals differ between the north and south hemispheres by about 1.4 deg. It is suggested that residual tilt angles show a slight systematic variation with phase in the activity cycle.
URI: http://hdl.handle.net/2248/3174
ISSN: 0038-0938
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Appears in Collections:IIAP Publications

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