Abstract:
Aims.
We investigate the properties of a sunspot light bridge, focusing on the changes produced by the impact of a plasma blob ejected
from a C-class flare.
Methods.
We observed a sunspot in active region NOAA 12544 using spectropolarimetric raster maps of the four Fe
i
lines around
15 655 Å with the GREGOR Infrared Spectrograph, narrow-band intensity images sampling the Fe
i
6173 Å line with the GREGOR
Fabry-Pérot Interferometer, and intensity broad-band images in
G
-band and Ca
ii
H
-band with the High-resolution Fast Imager. All
these instruments are located at the GREGOR telescope at the Observatorio del Teide, Tenerife, Spain. The data cover the time before,
during, and after the flare event. The analysis is complemented with Atmospheric Imaging Assembly and Helioseismic and Magnetic
Imager data from the Solar Dynamics Observatory. The physical parameters of the atmosphere at di
ff
erents heights were inferred
using spectral-line inversion techniques.
Results.
We identify photospheric and chromospheric brightenings, heating events, and changes in the Stokes profiles associated with
the flare eruption and the subsequent arrival of the plasma blob to the light bridge, after traveling along an active region loop.
Conclusions.
The measurements suggest that these phenomena are the result of reconnection events driven by the interaction of the
plasma blob with the magnetic field topology of the light bridge.
