Journal Article

Latitude migration of solar filaments

K. J. Li

in Monthly Notices of the Royal Astronomical Society

Published on behalf of The Royal Astronomical Society

Volume 405, issue 2, pages 1040-1046
Published in print June 2010 | ISSN: 0035-8711
Published online June 2010 | e-ISSN: 1365-2966 | DOI:
Latitude migration of solar filaments

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The Carte Synoptique catalogue of solar filaments from 1919 March–1989 December, corresponding to complete cycles 16–21, is utilized to show the latitudinal migration of filaments at low latitudes (less than 50°), and the latitudinal drift of solar filaments in each hemisphere in each cycle of the time interval is compared with the corresponding drift of sunspot groups. The latitudinal drift of filaments obviously differs from that of sunspot groups. At the beginning of a cycle, filaments (sunspot groups) migrate from latitudes of about 40° (28°) with a drift velocity of about 2.4 m s−1 (1.2 m s−1) toward the solar equator, reach latitudes of about 25° (20°) 4 yr later at the cycle maximum with a drift velocity of about 1.0 m s−1 (1.0 m s−1) and halt at about 8° (8°) at the end of the cycle. When solar activity is programmed into a solar cycle, the difference between the latitudes of appearance of filaments and sunspot groups becomes smaller and smaller. The difference rapidly decreases in the first and last ∼4 yr of a cycle, but barely decreases at all in the ∼4 yr after the cycle maximum. For filaments, the latitudinal drift velocity decreases in the first ∼7.5 yr of a cycle, but increases in the last ∼3.5 yr of the cycle. However, for sunspot groups the drift velocity always decreases over the whole cycle. The difference between the latitude drift of filaments in the northern and southern hemispheres is found not to be obvious. The latitudinal drift velocity of filaments differs slightly in the northern and southern hemispheres within a cycle. The physical implication behind the latitudinal drift of filaments is explored.

Keywords: methods: data analysis; Sun: activity; Sun: filaments, prominences

Journal Article.  4324 words.  Illustrated.

Subjects: Astronomy and Astrophysics

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