Magnetic helicity properties of emerging active regions determined from longitudinal photospheric magnetograms

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

Mysore

Congreso; COSPAR 2012; 2012

We study the emergence of solar active regions (ARs) to determine how their magnetic helicity properties affect the evolution of the photospheric flux observed in SOHO/MDI magnetograms.  We characterize the so called magnetic tongues (Luoni et al. 2011, Solar Phys. 270, 45), which are produced by the line of sight projection of the azimuthal component of the magnetic field in twisted emerging flux-tubes that form ARs. We determine and study the evolution of a series of parameters, such as the tilt angle, the polarity inversion line orientation, the magnetic flux, the size and the shape of the polarities and their tongues of 13 ARs observed between 2004 and 2007. We compare our results with the ones obtained for a single twisted toroidal model AR. We found good agreement betwwen the sign of magnetic helicity observed for the model and the ARs.