Limb Event Brightenings and Fast Ejection Using IRIS Mission Observations

Abstract

The Interface Region Imaging Spectrograph (IRIS) of the 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 the ultraviolet IRIS spectra reveal high-energy limb event brightenings (LEBs) at low chromospheric heights, around 1 Mm above the limb. They can be characterized as explosive events producing jets. We selected two 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 macrospicules on slit-jaw (SJ) images in Si IV and He II 304 A. 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 having 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 of up to 100 km/s in projection on the plane of the sky. The occurrence of erupting spicules and macrospicules from these regions is noticed from images taken before and after the spectra. The cool low first ionization potential (FIP) element simultaneous line emissions of the MgII h and k resonance lines do not clearly show a similar signature due to optical thickness effects but the Si IV 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.

24 pages, 16 figures., Accepted in Sol. Phys

References in corpus (3)

• Hot Explosions in the Cool Atmosphere of the Sun
• Statistical properties of the Disk Counterparts of Type II Spicules from simultaneous observations of RBEs in Ca II 8542 and Hα
• Alfvenic waves in polar spicules

Cited by in corpus (15)

• Investigating the Transition Region Explosive Events and Their Relationship to Network Jets
• Jet formation in solar atmosphere due to magnetic reconnection
• IRIS Observations of Spicules and Structures Near the Solar Limb
• I. Jet Formation and Evolution due to 3D Magnetic Reconnection
• Is It Small-scale Weak Magnetic Activity That Effectively Heats the Upper Solar Atmosphere?
• Small-scale solar jet formation and their associated waves and instabilities
• Synchronized Observations of Bright Points from the Solar Photosphere to Corona
• Characteristics of Chromospheric Oscillation Periods in Magnetic Bright Points (MBPs)
• Chromospheric peculiar off-limb dynamical events from IRIS observations
• Explosive Events in the Quiet Sun Near and Beyond the Solar Limb Observed with the Interface Region Imaging Spectrograph (IRIS)
• A new approach to kinetic energy flux at the different frequencies above the IRIS Bright Points
• Dynamics of Explosive Events by Interface Region Imaging Spectrograph
• Analysis of 3D plasma motions in a chromospheric jet formed due to magnetic reconnection
• Polar Coronal Plumes as Tornado-Like Jets
• Variation in the intensity ratio at each wavelength point of the Si iv 1394/1403 Å lines. Spectral diagnostics of a bifurcated eruption