Interactions between fast Down-flows and Fan-shaped Jets above a Penumbral Light Bridge using the Goode Solar Telescope

We present the analysis of high-resolution Hα observations of fan-shaped jets above a penumbral light bridge (LB) subject to external disturbance through fast down-flows in active region (AR) 12683 using data from the Goode Solar Telescope (GST) and the Atmospheric Imaging Assembly (AIA) on board the Solar Dynamics Observatory (SDO). Jets are observed with an occurrence rate of 5-6 min, reaching heights of 7-14 Mm above the LB with ascent speeds of 70 km/s and nearly parabolic trajectories. Associated bright fronts are seen as evidence of shock wave heating. We report the discovery of linear dark condensations of 0.45 Mm thickness that propagate ahead of the jet and shock, suggesting matter is being compressed in front of the shock. Fast down-flows of 40-80 km/s reach the South end of the LB with the same periodicity as the jets. The jets and associated small-scale linear structures exhibit horizontal motion, differential with height, along the LB axis at speeds of 35-55 km/s away from the interaction site. This speed is consistent with a magnetic field of 40-100 G. We propose that the fast down-flows triggers magnetic reconnection at the footpoint of the LB, which in turn drives the jets and the horizontal dynamics along the LB. We suggest that the linear fine-structure is the result of a fast magnetoacoustic wave propagating away from the reconnection site.