http://arxiv.org/abs/1507.06794
The Interface Region Imaging Spectrograph (IRIS) of the recently commissioned NASA Small Explorer mission provides significantly more complete and higher resolution spectral coverage of the dynamical conditions inside the chromosphere and Transition Region (TR) than has heretofore been available. Near the solar limb high temporal, spatial (0”3) and spectral resolution observations from ultraviolet IRIS spectra reveal high-energy limb event brightenings (LEBs) at low chromospheric height, near 1 Mm height above the limb. They can be characterized as explosive events producing jets. We selected 2 events showing spectra of a confined eruption just off or near the quiet Sun limb, the jet part showing obvious moving material with short duration large Doppler shifts in three directions identified as macro- spicules on slit-jaw (SJ) images in SiIV and HeII 304. The events are analyzed from a sequence of very close rasters taken near the central meridian and the South Pole limb. The processed SJ images and the simultaneously observed fast spectral sequences with large Doppler shifts, with a pair of red shifted elements together with a faster blue shifted element from almost the same position, are analyzed. Shifts correspond to velocities up to 100 km/s in projection on the plane of the limb. The occurrence of erupting spicules and macrospicules from these regions is noticed from images taken before and after the spectra. The cool low-FIP element simultaneous line emissions of the MgII h & k resonance lines do not clearly show a similar signature due to optical thickness effects but SiIV broad band SJ images do. The bidirectional plasma jets ejected from a small reconnection site are interpreted as the result of coronal loop-loop interactions leading to reconnection in nearby sites.
E. Tavabi, S. Koutchmy and L. Golub
Mon, 27 Jul 15
39/40
Comments: 25 pages, 15 figs., Accepted in Sol. Phys
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