INVESTIGADORES
MANDRINI Cristina Hemilse
congresos y reuniones científicas
Título:
Magnetic helicity properties of emerging active regions determined from longitudinal photospheric magnetogram
Autor/es:
POISSON, M.; LÓPEZ FUENTES, M.C.; MANDRINI, C.H.; DÉMOULIN, P.
Lugar:
Niza
Reunión:
Workshop; Flux Emergence Workshop 2013; 2013
Institución organizadora:
Observatoire de Paris
Resumen:
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 ARs
formed by twisted emerging flux-tubes. We analyze a set of 25 ARs observed between 2004 and 2010.
We only select regions for which the full emergence process is observed on the solar disk. In order
to minimize the background magnetic field contribution, we select cases that emerge in areas devoid
of remnant flux from older ARs. From the magnetograms we determine and study the evolution of
relevant parameters, in particular the tilt angle, the relative direction of the polarity inversion line
(defined as the PIL angle), and the magnetic flux of the ARs. Modeling the emergence of twisted
magnetic flux-tubes, we demonstrate that the PIL angle is a direct proxy for the evolution of the
tongues. To further characterize this evolution we compute and analyze weighted averages of the PIL
angle and the magnetic flux. We find that in 22 ARs from our set the presence of magnetic tongues
has a direct effect on the evolution of the PIL angle. For these cases, we are able to infer the magnetic
helicity sign from the obtained measurements and their computed averages. Since ARs with high
contents of magnetic helicity are, in general, the most productive in term of flares and CMEs, the
possible determination of their magnetic helicity properties from the very beginning of the emergence
can be a powerful forecast tool for solar activity.
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