IRIS and SDO Observations of Solar Jetlets Resulting from Network-edge Flux Cancelation

Abstract

Recent observations show that the buildup and triggering of minifilament eruptions that drive coronal jets result from magnetic flux cancelation at the neutral line between merging majority- and minority-polarity magnetic flux patches. We investigate the magnetic setting of 10 on-disk small-scale UV/EUV jets (jetlets, smaller than coronal X-ray jets but larger than chromospheric spicules) in a coronal hole by using IRIS UV images and SDO/AIA EUV images and line-of-sight magnetograms from SDO/HMI. We observe recurring jetlets at the edges of magnetic network flux lanes in the coronal hole. From magnetograms coaligned with the IRIS and AIA images, we find, clearly visible in nine cases, that the jetlets stem from sites of flux cancelation proceeding at an average rate of ~1.5 × 1018 Mx hr−1, and show brightenings at their bases reminiscent of the base brightenings in larger-scale coronal jets. We find that jetlets happen at many locations along the edges of network lanes (not limited to the base of plumes) with average lifetimes of 3 minutes and speeds of 70 km s−1. The average jetlet-base width (4000 km) is three to four times smaller than for coronal jets (~18,000 km). Based on these observations of 10 obvious jetlets, and our previous observations of larger-scale coronal jets in quiet regions and coronal holes, we infer that flux cancelation is an essential process in the buildup and triggering of jetlets. Our observations suggest that network jetlet eruptions might be small-scale analogs of both larger-scale coronal jets and the still-larger-scale eruptions producing CMEs.