Bibcode
Gömöry, P.; Beck, C.; Balthasar, H.; Rybák, J.; Kučera, A.; Koza, J.; Wöhl, H.
Referencia bibliográfica
Astronomy and Astrophysics, Volume 511, id.A14
Advertised on:
2
2010
Revista
Número de citas
54
Número de citas referidas
47
Descripción
Aims: We investigate the temporal evolution of magnetic flux
emerging within a granule in the quiet-Sun internetwork at disk center.
Methods: We combined IR spectropolarimetry of high angular
resolution performed in two Fe i lines at 1565 nm with
speckle-reconstructed G-band imaging. We determined the magnetic field
parameters by a LTE inversion of the full Stokes vector using the SIR
code, and followed their evolution in time. To interpret the
observations, we created a geometrical model of a rising loop in 3D. The
relevant parameters of the loop were matched to the observations where
possible. We then synthesized spectra from the 3D model for a comparison
to the observations. Results: We found signatures of magnetic
flux emergence within a growing granule. In the early phases, a
horizontal magnetic field with a distinct linear polarization signal
dominated the emerging flux. Later on, two patches of opposite circular
polarization signal appeared symmetrically on either side of the linear
polarization patch, indicating a small loop-like structure. The mean
magnetic flux density of this loop was roughly 450 G, with a total
magnetic flux of around 3 × 1017 Mx. During the ~12 min
episode of loop occurrence, the spatial extent of the loop increased
from about 1 to 2 arcsec. The middle part of the appearing feature was
blueshifted during its occurrence, supporting the scenario of an
emerging loop. There is also clear evidence for the interaction of one
loop footpoint with a preexisting magnetic structure of opposite
polarity. The temporal evolution of the observed spectra is reproduced
to first order by the spectra derived from the geometrical model. During
the phase of clearest visibility of the loop in the observations, the
observed and synthetic spectra match quantitatively. Conclusions:
The observed event can be explained as a case of flux emergence in the
shape of a small-scale loop. The fast disappearance of the loop at the
end could possibly be due to magnetic reconnection.
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Felipe García