Bibcode
DOI
Sobotka, Michal; Vázquez, Manuel; Bonet, J. A.; Hanslmeier, Arnold; Hirzberger, Johann
Bibliographical reference
The Astrophysical Journal, Volume 511, Issue 1, pp. 436-450.
Advertised on:
1
1999
Journal
Citations
75
Refereed citations
67
Description
Time series of high-resolution white-light images of six solar pores,
observed in 1993 and 1995 at the Swedish Vacuum Solar Telescope (La
Palma), are analyzed. The pores constitute an almost ideal laboratory in
which to study the interaction of a vertical magnetic field with
surrounding convective motions, without the perturbation of the inclined
magnetic field in the penumbra. Umbral dots observed in a large (D=8.9")
pore are similar to those in mature umbrae, but they live longer, are
brighter, and have a higher filling factor. Granular motions in the
vicinity of pores are driven by mesogranular flows. Motions toward the
pore dominate in the 2" zone around the pore boundary, while at larger
distances the granules move away from the pore. Pushed by these motions,
small granules and granular fragments located close to the pore border
sometimes penetrate into the pore, where they move inward as bright
short-lived features very similar to umbral dots. The capture of bright
features by the pore is probably a microscale manifestation of the
``turbulent erosion,'' which results in the decay of the pore. Formation
of a transitory penumbra-like structure at the border of the large pore
was observed simultaneously with the appearance of expanding elongated
granules, separated by dark filaments, in an adjacent granular field.
These effects can be interpreted as a consequence of emerging bipolar
magnetic ``loops'' caused by a temporary protrusion of opposite magnetic
polarity.