Characteristics of magnetic tongues over a solar cycle

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

Budapest, Hungría

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 different phases of the AR emergence by defining the variation of the tongue angleand  find  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 flux.  Thisevolution is compared with the emergence of a toroidal flux-rope model with non-uniformtwist.  The large variety of evolutions found for the tongues can only be reproduced whenusing a broad range of twist profiles; in particular, having a large variety of twist gradientsin the direction vertical to the photosphere.