Asymmetrical appearance of dark-cored filaments in sunspot penumbrae
Recent sunspot observations at unprecedented resolution have led to the discovery of dark cores in the bright filaments that form the penumbra ([CITE]). The discovery paper considered spots at disk center only, so the properties of the dark-cored filaments remain largely unknown. Here we analyze a s...
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Veröffentlicht in: | Astronomy and astrophysics (Berlin) 2004-09, Vol.424 (3), p.1049-1053 |
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Sprache: | eng |
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Zusammenfassung: | Recent sunspot observations at unprecedented resolution have led to the discovery of dark cores in the bright filaments that form the penumbra ([CITE]). The discovery paper considered spots at disk center only, so the properties of the dark-cored filaments remain largely unknown. Here we analyze a speckle-reconstructed time series of G-band and blue continuum images of a sunspot acquired with the Dutch Open Telescope. The target was located at an heliocentric angle of 27 deg. We confirm the existence of dark-cored penumbral filaments also in spots outside the disk center, and report on distinct differences between the center and limb-side penumbra. In the inner center-side penumbra, filaments are detected as two narrow bright streaks separated by a central obscuration. These structures move together as a single entity. On the limb side, dark cores are hardly seen. The time series is used to determine the sizes (~200-250 km), proper motions (~280 m s-1), and lifetimes ($\la$45 min) of typical dark-cored filaments. |
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ISSN: | 0004-6361 1432-0746 |
DOI: | 10.1051/0004-6361:20041380 |