34th Solar Physics Division Meeting, June 2003
Session 11 Photosphere and Chormosphere II
Oral, Tuesday, June 17, 2003, 1:30-3:30pm, Auditorium

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[11.04] Diffraction limited observations of flux concentrations and sunspot finestructure using adaptive optics

T.R. Rimmele (National Solar Observatory)

We present diffraction limited observations of magnetic flux concentrations and penumbral and umbral fine structure within an active region observed at disk center. We recorded g-band images, magnetograms, dopplergrams and narrow-band filtergrams using the Universal Birefringened Filter (UBF) at the Dunn Solar Telescope (DST). The adaptive optics system at the DST was used to achieve diffraction limited long exposure imaging with high signal-to-noise. The main results can be summarized as follows: Strong and spatially narrow downflows are observed at the edge of magnetic structures such as flux tubes, pores and the sunspot umbra. Flux concentrations observed as bright points in intensity expand by about 30-40% from a height close to where the continuum is formed and the height of formation for the g-band. For the particular sunspot observed and at a low altitude in the photosphere we find strong evidence for what appears to be vigorous, small-scale convection patterns in parts of the umbra and a light bridge. We observe extremely narrow (<0.”2) channels or sheets of downflowing plasma. We are able to identify individual penumbral fibrils in our data and find a small bright (hot) upflow and a more vertical field structure at the filament “head” near the umbral boundary. The field and flow turn to a nearly horizontal, dark structure within only about 0.”2 arcsec. We compare our results with theoretical model predictions.


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Bulletin of the American Astronomical Society, 35 #3
© 2003. The American Astronomical Soceity.