Solar Coronal Jets in Active Regions

Solar coronal jets are common in both coronal holes and in active regions. Recently, Sterling et al. (2015, Nature 523, 437), using data from Hinode/XRT and SDO/AIA, found that coronal jets originating in polar coronal holes result from the eruption of small-scale filaments (minifilaments). The jet bright point (JBP) seen in X-rays and hotter EUV channels off to one side of the base of the jet's spire develops at the location where the minifilament erupts, consistent with the JBPs being miniature versions of typical solar flares that occur in the wake of large-scale filament eruptions. Here we consider whether active region coronal jets also result from the same minifilament-eruption mechanism, or whether they instead result from a different process, such as emerging flux. Here we present observations of NOAA active region 12259, over 13-20 Jan 2015, using observations from Hinode/XRT, and from SDO/AIA and HMI. We focused on 13 standout jets that we identified from an initial survey of the XRT X-ray images, and we found many more jets in the AIA data set, which have higher cadence and more continuous coverage than our XRT data. All 13 jets originated from identifiable magnetic neutral lines; we further found magnetic flux cancelation to be occurring at essentially all of these neutral lines. At least 6 of those 13 jets were homologous, developing with similar morphology from nearly the same location, and in fact there were many more jets in the homologous sequence apparent in the higher-fidelity AIA data. Each of these homologous jets was consistent with minifilament-like ejections at the start of the jets. Other jets displayed a variety of morphologies, at least some of which were consistent with minifilament eruptions. For other jets however we have not yet clearly deciphered the driving mechanism. Our overall conclusions are similar to those of our earlier study of active region jets (Sterling et al. 2016, ApJ, 821, 100), where we found: some jets clearly to result from mini-filament eruptions; it was difficult to disentangle the mechanism of some other jets; and all of the jets originated from magnetic neutral lines, most of which were undergoing flux cancelation. This work was supported by funding from NASA/HGI, from the Hinode project, and (for FM) from the NASA/MSFC Research Experience for Undergraduates (REU) program.