A coronal hole jet observed with Hinode and the Solar Dynamics Observatory

Abstract

A small blowout jetwas observed at the boundary of the south polar coronal hole on 2011 February 8 at around 21:00UT. Images from the Atmospheric Imaging Assembly (AIA) on board the Solar Dynamics Observatory (SDO) revealed an expanding loop rising from one footpoint of a compact, bipolar bright point. Magnetograms from the Helioseismic Magnetic Imager (HMI) on board SDO showed that the jet was triggered by the cancelation of a parasitic positive polarity feature near the negative pole of the bright point. The jet emission was present for 25 min and it extended 30Mmfrom the bright point. Spectra from the Extreme Ultraviolet Imaging Spectrometer on board Hinode yielded a temperature and density of 1.6MK and 0.9-1.7×108 cm-3 for the ejected plasma. Line-of-sight velocities reached up to 250 kms-1 and were found to increase with height, suggesting plasma acceleration within the body of the jet. Evidence was found for twisting motions within the jet based on variations of the line-of-sight velocities across the jet width. The derived angular speed was in the range (9-12)×10-3 rad s-1, consistent with previous measurements from jets. The density of the bright point was 7.6×108 cm-3, and the peak of the bright point's emission measure occurred at 1.3MK, with no plasma above 3 MK.