Space–time evolution of Si IV from observations with the IRIS 1400 slit-jaw channel reveals linear, jet-like, intensity brightenings (red, almost vertical features in the right panels) at t = 10:41:00 UTC (bottom) and 11:22:20 UTC (top) that propagate at high speeds along an already existing spicule (which is outlined as a parabolic shape in the right panels). The left panels show maps of the SJI 1400 and the rectangles highlight the spicules. For the space–time plot (right panels), we follow the intensity (in IRIS Data Numbers per second) along the major axis of the rectangles in the left plot. The black vertical lines in the space–time plots are caused by data gaps in the timeseries.

(Animations (a) and (b) of this figure are available.)

The video/animation of this figure is available in the online journal.