IAFE   05512
INSTITUTO DE ASTRONOMIA Y FISICA DEL ESPACIO
Unidad Ejecutora - UE
congresos y reuniones científicas
Título:
Active region helicity properties from magnetic tongues
Autor/es:
M. POISSON; M. LÓPEZ FUENTES; C. H. MANDRINI; P. DÉMOULIN
Lugar:
Moscú
Reunión:
Congreso; 40th COSPAR Scientific Assembly 2014; 2014
Institución organizadora:
Committee on Space Research (COSPAR)
Resumen:
p { margin-bottom: 0.08in; }
We study photospheric
magnetic tongues to infer the magnetic helicity sign of a large set
of active regions (ARs) observed during solar cycle 23. The tongues
appear during the emergence of twisted toroidal magnetic flux tubes
that form ARs due to the the azimuthal component of the magnetic
field around the torus axis. The projection of the azimuthal
component in the normal direction to the photosphere produces the
tongues as observed in photospheric magnetograms. The method to
compute the helicity sign is based on the determination and evolution
of the polarity inversion line (PIL) and it's relative orientation
respect to the direction of the AR main bipolar axis (the AR's tilt).
We analyze a set of 150 bipolar ARs observed with SOHO/MDI between
1996 and 2010. The PIL method, as tested in previous works, needs ARs
with simple bipolar structures and devoid of backgroud magnetic
remnants in order to provide reliable computations. Therefore, the
low number of sunspots registered along the minimum of cycle 23 to 24
is a favourable scenario to find simple isolated ARs. We analyze a
series of statistical properties of the studied ARs, such as the
latitudinal and hemispherical dependence of the magnetic helicity,
the tilt, the total unsigned magnetic flux and the presence of
asymmetries between the main polarities.