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Astrophysics Research Centre

School of Mathematics and Physics

Fine-scale Structure and Motion of Penumbral Filaments Revealed with Hinode G-band and Ca II H Filtergrams

  • Submitted by: Yoshinori Suematsu, National Astronomical Observatory of Japan
  • Authors: Y. Suematsu
  • Session: Thursday morning posters.

Sunspot penumbrae are interesting target to study phenomena caused by the interaction of magnetized flux tubes with thermal convection. It is likely that a rising flux tube model can explain the origin of most penumbral phenomena such as bright grains which appear in the outer part of penumbra, tending to migrate toward inside umbra, and the Evershed flow which takes place preferentially in bright (hot) grains/filaments in the inner penumbra, but in dark (cool) filaments in the outer penumbra. However, observation is not always consistent with this picture. To constrain the model of penumbral filaments, we studied fine-scale structure and motion in penumbra, by improving time sequence images from Hinode G-band and Ca II H filtergrams. Fine structures of close to 0.1 arcsec were revealed by using a super- resolution technique which can derive structures finer than the diffraction-limit of the Hinode/SOT. The grains are prominent in the inner penumbra in G-band but hard to see in Ca II H. On the other hand, Ca II H shows bright tapered structures in mid to outer part of penumbra except for light-bridge forming regions, which are mostly slowly varying like G-band grains and hard to distinguish from the so-called penumbral micro-jets unless their lifetimes are measured. The Evershed flow gets prominent in Ca II H as fast moving bright thin streaks of a chain of small blobs rather than moving dark elongated clouds. Those bright features in Ca II H seem to indicate that additional heating to convection take place in the lower chromosphere of penumbra.

public/hinode9/schedule/session-07p/v0090.txt · Last modified: 2015/07/30 01:39 (external edit)

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