Quasiperiodic Microjets Driven by Granular Advection as Observed With High-resolution Imaging at He i 10830 Å

With high-resolution narrowband He i 10830 angstrom filtergrams from Goode Solar Telescope, we give an extensive analysis for four granule-sized microeruptions which appear as the gentle ejection of material in He i 10830 angstrom band. The analysis was aided with the EUV data from Atmospheric Imaging Assembly and line-of-sight magnetograms from the Helioseismic and Magnetic Imager on board the Solar Dynamics Observatory. The microeruptions are situated on magnetic polarity inversion lines (PILs), and their roots are accurately traced down to intergranular lanes. Their durations are different: two microeruptions are repetitive microjets, lasting similar to 50 and 27 minutes respectively, while the other two events are singular, lasting similar to 5 minutes. For the two microjets, they are continuous and recurrent in the He i 10830 angstrom band, and the recurrence is quasiperiodic with a period of similar to 5 minutes. We found that only transient cospatial EUV brightenings are observed for the longer duration microjets and EUV brightenings are absent for the two singular microeruptions. What is essential to the longer duration microjets is that granules with the concentration of a positive magnetic field persistently transport the magnetic field to the PILs, canceling the opposite magnetic flux and making the base of the two microjets and the underlying granules migrate with the speed of similar to 0.25 and 1.0 km s(-1). The observations support the scenario of magnetic reconnection for the quasiperiodic microjets and further show that the reconnection continuously generates multitemperature components, especially the cool component with chromospheric temperature. In addition, the ongoing reconnection is modulated by p-mode oscillations inside the Sun.

Automated summary

This study provides an extensive analysis of four granule-sized microeruptions observed in the He i 10830 angstrom band, with their roots traced down to intergranular lanes. The microeruptions exhibit different durations and behaviors, with two being repetitive microjets and the other two being singular events. Transient cospatial EUV brightenings were observed for longer duration microjets, while absent for singular microeruptions. The observations suggest that magnetic reconnection occurs continuously and generates multitemperature components, modulated by p-mode oscillations inside the Sun.