Hinode EUV Study of Jets in the Sun's South Polar Corona

A number of coronal bright points and associated plasma jet features were seen in an observation of the South polar coronal hole during 2007 January. The 40" wide slot was used at the focus of the Hinode EUV Imaging Spectrometer to provide spectral images for two of these events. Light curves are plotted for a number of emission lines that include He II 256Å (0.079MK) and cover the temperature interval from 0.4MK to 5.0MK. Jet speed measurements indicate values less than the escape velocity. The light curves show a post-jet enhancement in a number of the cooler coronal lines indicating that after a few minutes cooling, the plasma fell back to its original acceleration site. This behavior has not been previously observed by e.g., the Yohkoh Soft X-ray Telescope due to the comparatively high temperature cut-off in its response. The observations are consistent with the existing models that involve magnetic reconnection between emerging flux and the ambient open field lines in the polar coronal hole. However we do not have sufficient coverage of lines from lower temperature ion species to register the Hα-emitting surge material that is associated with some of these models.