Magnetic Correspondence between Moving Magnetic Features and Penumbral Magnetic Fields
M. Kubo (Univ. of Tokyo) and T. Shimizu (JAXA/ISAS)
Moving magnetic features (MMFs) are small magnetic elements
moving outward in the moat region surrounding mature sunspots.
We investigate vector magnetic fields and horizontal motion of MMFs
including non-isolated MMFs in addition to the classical isolated MMFs
around a simple sunspot observed with the Advanced Stokes Polarimeter
and SOHO/MDI. The non-isolated MMFs occupy most of the moat region,
and have nearly horizontal magnetic fields with both polarities.
We find that the isolated MMFs located on the lines extrapolated from
the horizontal components of the penumbral fluted structure, in which
horizontal fields and relatively vertical fields are alternately located,
have magnetic fields similar to the non-isolated MMFs. This suggests
that such MMFs are part of horizontal fields extended from the penumbra.
We find that the isolated MMFs located on the lines extrapolated from
the vertical components of the fluted structure have vertical fields
with polarity same as the sunspot. This is clear evidence that such MMFs
are detached from the vertical components of the penumbra. Their flux
transport rate is estimated to be 1-3 times larger than a flux loss
rate of the sunspot. The isolated vertical MMFs alone can be responsible
for decaying the sunspot.
Correspondence
Masahito Kubo (masahito.kubo@nao.ac.jp), University of Tokyo
presentation
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