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Dark cores in sunspot penumbral filaments

Nature volume 420, pages 151–153 (2002)Cite this article

Abstract

Sunspot umbrae—the dark central regions of the spots—are surrounded by brighter filamentary penumbrae, the existence of which remains largely inexplicable1. The penumbral filaments contain magnetic fields with varying inclinations2 and are associated with flowing gas3,4,5, but discriminating between theoretical models6,7,8 has been difficult because the structure of the filaments has not hitherto been resolved. Here we report observations of penumbral filaments that reveal dark cores inside them. We cannot determine the nature of these dark cores, but their very existence provides a crucial test for any model of penumbrae. Our images also reveal other very small structures, in line with the view that many of the fundamental physical processes in the solar photosphere occur on scales smaller than 100 km.

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Figure 1: Part of the largest spot in active region 10030 on 15 July 2002 recorded with the Swedish 1-m Solar Telescope using adaptive optics (as are all images shown here).
Figure 2: Examples of penumbral filaments with dark cores.
Figure 3: Thin dark features in active region 10030 on 15 July 2002.

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Acknowledgements

The Swedish 1-m Solar Telescope is operated on the island of La Palma by the Royal Swedish Academy of Sciences in the Spanish Observatorio del Roque de los Muchachos of the Instituto de Astrofísica de Canarias.

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Authors and Affiliations

  1. The Institute for Solar Physics of the Royal Swedish Academy of Sciences, AlbaNova University Centre, SE-106 91, Stockholm, Sweden

    Göran B. Scharmer, Boris V. Gudiksen, Dan Kiselman, Mats G. Löfdahl & Luc H. M. Rouppe van der Voort

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  1. Göran B. Scharmer
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  2. Boris V. Gudiksen
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  3. Dan Kiselman
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  4. Mats G. Löfdahl
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  5. Luc H. M. Rouppe van der Voort
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Correspondence to Dan Kiselman.

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Scharmer, G., Gudiksen, B., Kiselman, D. et al. Dark cores in sunspot penumbral filaments. Nature 420, 151–153 (2002). https://doi.org/10.1038/nature01173

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