Magnetic Untwisting in Most Solar X-Ray Jets

From 54 Xray jets observed in the polar coronal holes by Hinode's XRay Telescope (XRT) during coverage in movies from Solar Dynamic Observatory's Atmospheric Imaging Assembly (AIA) taken in its He II 304 band at a cadence of 12 s, we have established a basic characteristic of solar Xray jets: untwisting motion in the spire. In this presentation, we show the progression of few of these Xray jets in XRT images and track their untwisting in AIA He II images. From their structure displayed in their XRT movies, 19 jets were evidently standard jets made by interchange reconnection of the magneticarcade base with ambient open field, 32 were evidently blowout jets made by blowout eruption of the base arcade, and 3 were of ambiguous form. As was anticipated from the >10,000 km span of the base arcade in most polar Xray jets and from the disparity of standard jets and blowout jets in their magnetic production, few of the standard Xray jets (3 of 19) but nearly all of the blowout Xray jets (29 of 32) carried enough cool (T is approximately 105 K) plasma to be seen in their He II movies. In the 32 Xray jets that showed a cool component, the He II movies show 10100 km/s untwisting motions about the axis of the spire in all 3 standard jets and in 26 of the 29 blowout jets. Evidently, the open magnetic field in nearly all blowout Xray jets and probably in most standard Xray jets carries transient twist. This twist apparently relaxes by propagating out along the open field as a torsional wave. Highresolution spectrograms and Dopplergrams have shown that most TypeII spicules have torsional motions of 1030 km/s. Our observation of similar torsional motion in Xray jets strengthens the case for TypeII spicules being made in the same way as Xray jets, by blowout eruption of a twisted magnetic arcade in the spicule base and/or by interchange reconnection of the twisted base arcade with the ambient open field. This work was funded by NASA's Heliophysics Division through its LWS TRT Program and its Hinode Project, and by NSF through its Research Experience for Undergraduates Program