Unusual Filaments Inside the Umbra

Abstract

We analyze several unusual filamentary structures, which appeared in the umbra of one of the sunspots in AR 11302. They do not resemble typical light bridges, neither in morphology, nor in evolution. We analyze data from SDO/HMI to investigate their temporal evolution, Hinode/SP for photospheric inversions, IBIS for chromospheric imaging, and SDO/AIA for the overlying corona. Photospheric inversions reveal a horizontal, inverse Evershed flow along these structures, which we call umbral filaments. Chromospheric images show brightenings and energy dissipation, while coronal images indicate that bright coronal loops seem to end in these umbral filaments. These rapidly evolving features do not seem to be common, and are possibly related to the high flare-productivity of the active region. Their analysis could help to understand the complex evolution of active regions.

References in corpus (4)

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• Supersonic Downflows in a Sunspot Light Bridge
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Cited by in corpus (18)

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• Absolute velocity measurements in sunspot umbrae
• Evershed and counter-Evershed flows in sunspot MHD simulations
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• Properties of the Umbral Filament Observed in Active Region NOAA 12529
• The formation of an atypical sunspot light bridge as a result of large-scale flux emergence
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• Magnetic connectivity between the light bridge and penumbra in a sunspot
• How rare are counter Evershed flows?
• Long-Term Evolution of Three Light Bridges Developed on the Same Sunspot
• Onset of penumbra formation
• Expulsion of counter Evershed flows from sunspot penumbrae
• The MODEST catalog of depth-dependent spatially coupled inversions of sunspots observed by Hinode/SOT-SP
• Penumbral brightening events observed in AR NOAA 12546
• Apparent Transverse Motion of Light Bridges Coupled to Coronal Loop Dynamics
• An Unusual Velocity Field in a Sunspot Penumbra