Bibcode
Kuckein, C.; Martínez-Pillet, V.; Centeno, R.
Bibliographical reference
Astronomy and Astrophysics, Volume 542, id.A112
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6
2012
Journal
Citations
41
Refereed citations
36
Description
Context. Paper I presents the magnetic structure, inferred for the
photosphere and the chromosphere, of a filament that developed in active
region (AR) NOAA 10781, observed on 2005 July 3 and July 5. Aims:
In this paper we complement those results with the velocities retrieved
from Doppler shifts measured at the chromosphere and the photosphere in
the AR filament area. Methods: The velocities and magnetic field
parameters were inferred from full Stokes inversions of the photospheric
Si i 10 827 Å line and the chromospheric He i 10 830 Å
triplet. Various inversion methods with different numbers of atmospheric
components and different weighting schemes of the Stokes profiles were
used. The velocities were calibrated on an absolute scale.
Results: A ubiquitous chromospheric downflow is found in the faculae
surrounding the filament, with an average velocity of 1.6 km
s-1. The filament region, however, displays upflows in the
photosphere on both days, when the linear polarization (which samples
the transverse component of the fields) is given more weight in the
inversions. The upflow speeds of the transverse fields in the filament
region average -0.15 km s-1. In the chromosphere, the
situation is different for the two days of observation. On July 3, the
chromospheric portion of the filament is moving upward as a whole with a
mean speed of -0.24 km s-1. However, on July 5 only the
section above an orphan penumbra shows localized upflow patches, while
the rest of the filament is dominated by the same downflows observed
elsewhere in the facular region. Photospheric supersonic downflows that
last for tens of minutes are detected below the filament, close to the
PIL. Conclusions: The observed velocity pattern in this AR
filament strongly suggests a scenario where the transverse fields are
mostly dominated by upflows. The filament flux rope is seen to be
emerging at all places and both heights, with a few exceptions in the
chromosphere. This happens within a surrounding facular region that
displays a generalized downflow in the chromosphere and localized
downflows of supersonic character at the photosphere. No large scale
downflow of transverse field lines is observed at the photosphere.
Appendices A and B are available in electronic form at http://www.aanda.org
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