EVOLUTION OF THE MAGNETIC FIELD INCLINATION IN A FORMING PENUMBRA

We describe the evolution of the magnetic and velocity fields in the annular zone around a pore a few hours before the formation of its penumbra. We detected the presence of several patches at the edge of die annular zone, with a typical size of about 1". These patches are characterized by a ra...

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Bibliographic Details
Published inThe Astrophysical journal Vol. 784; no. 1; pp. 1 - 6
Main Authors Romano, P, Guglielmino, S L, Cristaldi, A, Ermolli, I, Falco, M, Zuccarello, F
Format Journal Article
LanguageEnglish
Published United States 20.03.2014
Subjects
Annular
ASTROPHYSICS, COSMOLOGY AND ASTRONOMY
CHROMOSPHERE
EVOLUTION
Formations
Inclination
MAGNETIC FIELDS
Penumbras
PHOTOSPHERE
PLASMA
Porosity
SUN
VELOCITY
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Summary:We describe the evolution of the magnetic and velocity fields in the annular zone around a pore a few hours before the formation of its penumbra. We detected the presence of several patches at the edge of die annular zone, with a typical size of about 1". These patches are characterized by a rather vertical magnetic field with polarity opposite to that of the pore. They correspond to regions of plasma upflow up to 2.5 km s super(-1) and are characterized by radially outward displacements with horizontal velocities up to 2 km s super(-1). We interpret these features as portions of the pore magnetic field lines returning beneath the photosphere being progressively stretched and pushed down by the overlying magnetic fields. Our results confirm that the penumbra formation results from changes in the inclination of the field lines in the magnetic canopy overlying the pore, until they reach the photosphere.
Bibliography:ObjectType-Article-1
SourceType-Scholarly Journals-1
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ISSN:0004-637X
1538-4357
DOI:10.1088/0004-637X/784/1/10