Dynamical Properties of He II EUV Surges that are Components of Solar Active Region Coronal Jets

We study dynamics of solar He II 304-Å EUV surges from around a sunspot approaching the west

limb, using images from the Atmospheric Imaging Assembly (AIA) on the Solar Dynamics

Observatory (SDO) satellites. These jets were initially selected because of their strong signatures

in X-rays when observed with the X-Ray Telescope (XRT) on the Hinode spacecraft, and thus we

are studying EUV (304-Å) surges that are clear counterparts to X-ray jets. Preliminary findings,

based on 10 jets, show that on average they reach lengths of 6.5 ±1.5 x 10⁴ km, and have lifetimes of 33.1 ± 8.8 minutes. For eight of our jets where we could make reliable assessments,

all show evidence for twisting motion in their initial stages. On average, this twisting ends when the jets have achieved only about one-half (44% on average) of their maximum extents.

Because in these cases the jets kept rising following the end of the twisting, and because in none of these cases did the twisting continue beyond the peak length of the jets, these observations

support that torsional magnetic pulses injected at the jet bases assist in propelling the jets outward.

This work was supported by the REU program at UAH/MSFC, by the NASA's HGI program, and by

the Hinode project at MSFC.