A new type of small-scale downflow patches in sunspot penumbrae

Abstract

A sunspot penumbra is observationally examined to reveal properties of small-scale flow structures and how they are related to the filamentary magnetic structures and the Evershed flow. We also study how the photospheric dynamics is related to chromospheric activities. The study is based on data analysis of spectro-polarimetric observations of photospheric Fe I lines with the Solar Optical Telescope aboard Hinode in a sunspot penumbra at different heliocentric angles. Vector magnetic fields and velocities are derived using the spectro-polarimetric data and a Stokes inversion technique. An observation with a Ca II H filtergram co-spatial and co-temporal with the spectro-polarimetric one is also used to study possible chromospheric responses. We find small patches with downflows at photospheric layers. The downflow patches have a size of 0.5" or smaller and have a geometrical configuration different from that of the Evershed flow. The downflow velocity is about 1 km/s at lower photspheric layers, and is almost zero in the upper layers. Some of the downflow patches are associated with brightenings seen in Ca II H images. The downflows are possible observational signatures of downward flows driven by magnetic reconnection in the interlaced magnetic field configuration, where upward flows make brightenings in the chromosphere. Another possibility is that they are concentrated downward flows of overturning magnetoconvection.

9 pages, 7 figures, accepted for publication in Astronomy & Astrophysics

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Cited by in corpus (21)

• Numerical sunspot models: Robustness of photospheric velocity and magnetic field structure
• Peripheral downflows in sunspot penumbrae
• Structure of sunspot penumbral filaments: a remarkable uniformity of properties
• Depth-dependent global properties of a sunspot observed by Hinode using the Solar Optical Telescope/Spectropolarimeter
• Evidence for a Transition Region response to penumbral microjets in sunspots
• The velocity field of sunspot penumbrae II. Return flow and magnetic fields of opposite polarity
• Observationally based models of penumbral microjets
• Magnetic fields of opposite polarity in sunspot penumbrae
• Microjets in the penumbra of a sunspot
• Anomalous flows in a sunspot penumbra
• Temporal Evolution of the Inverse Evershed Flow
• Supersonic Downflows at the Umbra-Penumbra Boundary of Sunspots
• Can overturning motions in penumbral filaments be detected?
• 3D magnetic field configuration of small-scale reconnection events in the solar plasma atmosphere
• Sunspot penumbral filaments intruding into a light bridge and the resultant reconnection jets
• Penumbral micro-jets at high spatial and temporal resolution
• A multi-diagnostic spectral analysis of penumbral microjets
• The dark side of penumbral microjets: Observations in Hα
• Temporal evolution of short-lived penumbral microjets
• The MODEST catalog of depth-dependent spatially coupled inversions of sunspots observed by Hinode/SOT-SP
• Bright Dots and Coronal Plume Formation in Sunspot Penumbra