Inferring the writhe of solar active regions

LÓPEZ FUENTES, M.C.; MANDRINI, C.H.; DÉMOULIN, P.; VAN DRIEL-GESZTELYI, L.

GEOFíSICA INTERNACIONAL

Insituto de Geofísica de la UNAM

Año: 2004 vol. 43 p. 83 - 88

0016-7169

ABSTRACT: We study the long-term evolution of bipolar active regions in which the main polarities are observed to rotate one about !he other along several solar rotations. We propose that this peculiar evolution is due to the emergence of distorted magnetic flux tubes.We are able to infer the sign ofthe writhe helicity ofthe flux tubes from the rotation ofthe axisjoining the main positive and negative polarities. The origin of the deformations may be explained by !he development of a kink instability. Another possibility is !he interaction with plasma motions during the ascent of the flux tubes in the Convective Zone. We discuss the role of the Corilis force, convective turbulence and other large-scale motions in this process.