Supersonic Downflows in a Sunspot Light Bridge

Abstract

We report the discovery of supersonic downflows in a sunspot light bridge using measurements taken with the spectropolarimeter on board the Hinode satellite. The downflows occur in small patches close to regions where the vector magnetic field changes orientation rapidly, and are associated with anomalous circular polarization profiles. An inversion of the observed Stokes spectra reveals velocities of up to 10 km/s, making them the strongest photospheric flows ever measured in light bridges. Some (but not all) of the downflowing patches are cospatial and cotemporal with brightness enhancements in chromospheric Ca II H filtergrams. We suggest that these flows are due to magnetic reconnection in the upper photosphere/lower chromosphere, although other mechanisms cannot be ruled out.

4 pages, 5 figures, Published in ApJ Letters

References in corpus (3)

• The Solar Optical Telescope for the Hinode Mission: An Overview
• Formation Process of a Light Bridge Revealed with the Hinode Solar Optical Telescope
• Detection of opposite polarities in a sunspot light bridge: evidence of low-altitude magnetic reconnection

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• Statistical Investigation of Supersonic Downflows in the Transition Region above Sunspots
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• 3D magnetic field configuration of small-scale reconnection events in the solar plasma atmosphere
• Detection of Opposite Magnetic Polarity in a Light Bridge: Its Emergence and Cancellation in association with LB Fan-shaped Jets
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• Sustained heating of the chromosphere and transition region over a sunspot light bridge
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