Comparing High-speed Transition Region Jets in Coronal Holes and Quiet Sun Regions

Abstract:

The complicated energy transfer and plasma motion in the transition region, between the photosphere and the corona, may play a significant role in the formation and acceleration of the solar wind. New observations from the Interface Region Imaging Spectrograph (IRIS) have revealed unprecedented levels of detail in this less-studied region. Coronal holes in particular are a likely source of solar wind material, though the formation and acceleration mechanisms of the fast solar wind are still largely unknown. In our previous work, we have reported the prevalence of small-scale high-speed (~80-250 km/s) jets with transition region temperatures from the network structures of coronal holes. Here we undertake a comparative study of these short-lived episodic network jets in a coronal hole region and a quiet sun region using IRIS sit-and-stare slit-jaw imaging in the 1330 Angstrom (C II) passband. The pointing coordinates, exposure time, observing cadence, and field of view of both observations are all identical. Our preliminary study suggests that the speeds and lengths of the network jets may differ between quiet sun and coronal hole regions. The quiet sun region exhibits many compact bright regions with sizes of 5-10 arcseconds which produce very few jets. The jets that do exist tend to propagate at much slower speeds over smaller distances than their coronal hole counterparts. Comparatively, in the coronal hole, such compact regions are almost absent and all network patches are permeated by the intermittent high-reaching jets. Such a difference suggests that magnetic loops are much smaller in the coronal hole and the network jets are produced at low heights. The recurrence frequency seems to be higher in the coronal hole region, with many of the isolated quiet sun region jets demonstrating curved trajectories.

This work is supported under contract 8100002705 from Lockheed-Martin to SAO and by the NSF-REU solar physics program at SAO, grant number AGS-1263241.