The characteristics of magnetic tongues over a solar cycle

DÉMOULIN, P.; POISSON, M.; MANDRINI, C.H.; LÓPEZ FUENTES, M.C.

Workshop; Flux Emergence Workshop 2017; 2017

We study the twist of newly emerged bipolar ARs from the evolution of magnetic tonguesobserved in photospheric line-of-sight magnetograms over the full Solar Cycle 23 and thebeginning of Cycle 24. Our results show that the hemispherical rule obtained using thetongues as a proxy of the twist has a weak sign dominance (53% in the southern hemisphereand 58% in the northern hemisphere). We characterize the strength of the magnetic tonguesduring dierent phases of the AR emergence by dening the variation of the tongue angleand nd that there is a tendency of the tongues to be stronger during the beginning ofthe emergence and to become weaker as the AR reaches its maximum magnetic ux. Thisevolution is compared with the emergence of a toroidal ux-rope model with non-uniformtwist. The large variety of evolutions found for the tongues can only be reproduced whenusing a broad range of twist proles; in particular, having a large variety of twist gradientsin the direction vertical to the photosphere.