Spectroscopic and Stereoscopic Observations of the Solar Jets

Abstract

We present a comprehensive study of a series of recurrent jets that occurred at the periphery of the NOAA active region 12114 on 2014 July 7. These jets were found to share the same source region and exhibited rotational motions as they propagated outward. The multi-wavelength imaging observations made by the AIA and IRIS telescopes reveal that some of the jets contain cool plasma only, while some others contain not only cool but also hot plasma. The Doppler velocities calculated from the IRIS spectra show a continuous evolution from blue to red shifts as the jet motions change from upward to downward. Additionally, some jets exhibit opposite Doppler shifts on their both sides, indicative of rotating motions along their axes. The inclination angle and three-dimensional velocity of the largest jet were inferred from the imaging and spectroscopic observations, which show a high consistence with those derived from the stereoscopic analysis using dual-perspective observations by SDO/AIA and STEREO-B/EUVI. By relating the jets to the local UV/EUV and full-disk GOES X-ray emission enhancements, we found that the previous five small-scale jets were triggered by five bright points while the last/largest one was triggered by a C1.6 solar flare. Together with a number of type III radio bursts generated during the jet eruptions as well as a weak CME that was observed in association with the last jet, our observations provide evidences in support of multi-scale magnetic reconnection processes being responsible for the production of jet events.

Observation and modelling of solar jets

“…Cheung et al [194] studied four homologous helical jets at transition region temperatures, which showed evidence of oppositely directed flows with components reaching Doppler velocities of ±100 km s −1 , and the magnetic twists needed for the helical jets were found to be supplied by emerging current-carrying magnetic fields (figure 5). Lu et al [195] studied a recurrent jet event using spectroscopic and stereoscopic observations, in which the Doppler velocities were about ±90 km s −1 , which is consistent with the value derived from stereoscopic imaging observations. A statistical study performed by Kayshap et al [196] indicated that rotational motion is omnipresent in network jets, which can be detected as blueshift on one edge and redshift on the other at a mean rotational velocity of about 49.56 km s −1 .…”

Observation and Modeling of Solar Jets

“…Cheung et al [194] studied four homologous helical jets at transition region temperatures, which showed evidence of oppositely directed flows with components reaching doppler velocities of ±100 km s −1 , and the magnetic twist needed for the helical jets were found to be supplied by emerging current-carrying magnetic fields (see Figure 5). Lu et al [195] studied a recurrent jet event using spectroscopic and stereoscopic observations, in which the doppler velocities were about ±90 km s −1 , consistent with the value derived from stereoscopic imaging observations. Recent statistical study performed by Kayshap et al [196] indicated that rotational motion is omnipresent in network jets, which can be detected as blueshift on one edge and redshift on the other at a mean rotational velocity of about 49.56 km s −1 .…”

Solar Jets: SDO and IRIS Observations in the Perspective of New MHD Simulations

“…Radio Type III bursts were also often associated with surges, suggesting that surges followed open magnetic field lines or very large loops (Chiuderi-Drago et al, 1986;Kundu et al, 1995). This idea has been confirmed by using NLFFF extrapolation showing how nonthermal types III associated with jets escape along open field lines at the edge of close structures over active regions (Lu et al, 2019;Mulay et al, 2019). Schmieder et al (1983), Schmieder et al (1984) reported on the recurrence of Hα and C IV surges with a time delay between two jet ejections of 15-30 min.…”

“…Blue and red shift pattern is not always interpreted as a possible rotation (Schmieder et al, 1983;Tiwari et al, 2019), However, frequently, it is defined that the characteristics of the twisting jet is relatively common and does not depend on the temperature or the coronal environment. Twisting has been found in penumbra jets (Tiwari et al, 2018), and in active region jets (Lu et al, 2019;Joshi et al, 2021b) using Si IV, C II, and Mg II lines observed by the IRIS. The interpretation of the small jets is based on cartoons showing magnetic reconnection in mixed local magnetic field polarities.…”