IAFE   05512
INSTITUTO DE ASTRONOMIA Y FISICA DEL ESPACIO
Unidad Ejecutora - UE
artículos
Título:
Homologous flares and magnetic field topology in active region NOAA 10501 on 20 November 2003
Autor/es:
CHANDRA, R.; SCHMIEDER, B.; MANDRINI, C.H.; D¨¦MOULIN, P.; PARIAT, E.; TOROK, T.; UDDIN, W.
Revista:
SOLAR PHYSICS
Editorial:
SPRINGER
Referencias:
Año: 2010
ISSN:
0038-0938
Resumen:
We present and interpret observations of two morphologically homologous
flares that occurred in active region (AR) NOAA 10501 on 20 November
2003. Both flares displayed four homologous H¦Á ribbons and were
both accompanied by coronal mass ejections (CMEs). The central flare
ribbons were located at the site of an emerging bipole in the centre of
the active region. The negative polarity of this bipole fragmented in
two main pieces, one rotating around the positive polarity by ¡Ö
110¡ã within 32 hours. We model the coronal magnetic field and
compute its topology, using as boundary condition the magnetogram
closest in time to each flare. In particular, we calculate the location
of quasi-separatrix layers (QSLs) in order to understand the
connectivity between the flare ribbons. Though several polarities were
present in AR 10501, the global magnetic field topology corresponds to a
quadrupolar magnetic field distribution without magnetic null points.
For both flares, the photospheric traces of QSLs are similar and match
well the locations of the four H¦Á ribbons. This globally unchanged
topology and the continuous shearing by the rotating bipole are two key
factors responsible for the flare homology. However, our analyses also
indicate that different magnetic connectivity domains of the quadrupolar
configuration become unstable during each flare, so that magnetic reconnection proceeds differently in both events.