Bibcode
Sainz Dalda, A.; López Ariste, A.
Bibliographical reference
Astronomy and Astrophysics, Volume 469, Issue 2, July II 2007, pp.721-729
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7
2007
Journal
Citations
8
Refereed citations
6
Description
Context: The behaviour of both ephemeral regions and moving magnetic
features has been often described for the photospheric layer, but not
for the chromosphere. Both magnetic structures are related to the decay
of active regions, but their actual role is not yet clear. Aims:
Our aim is to observe and understand the behaviour of these structures
in the chromosphere. Methods: We performed simultaneous
photospheric and chromospheric spectropolarimetric observations of an
ephemeral region and a moving magnetic feature. A new code developed for
the reduction of spectropolarimetric data of several wavelengths
observed simultaneously was used here for the first time and will be
described here for future reference. The resulting Stokes profiles are
analysed in detail. Results: The Stokes V profiles of Fe i 6301
and 6302 Å are reversed in polarity with respect to the
chromospheric Ca ii 8498 and 8542 Å in the cases shown. They
reveal a reversed magnetic field topology between these layers for both
structures. The time evolution of the ephemeral region results in a
cancellation of the chromospheric signal, while the ratio of Stokes V
amplitudes of Fe i 6301 and 6302 Å simultaneously informs us of a
strengthening of the photospheric field. A scenario of the evolution of
the ephemeral region is consequently suggested. Conclusions: The
moving magnetic feature reveals itself as an exclusively photospheric
feature, similar to the ephemeral region in the initial stages of its
emergence. As the loop emerges into the chromosphere it is slowed down
and does not reach the corona. Most probably, the opposite polarity
background in the chromosphere prevents ascent into corona.