The Structure and Dynamics of the Quiet Corona from Observations with the Extreme Ultraviolet Imaging Spectrometer on Hinode
The goal of the Hinode mission is to provide an observational basis for understanding the heating and acceleration of coronal plasmas. On 2007 January 20, the Extreme ultraviolet Imaging Spectrometer performed a raster of a quiet region near Sun center. Maps of intensities, velocities, and electron densities derived from these observations are presented and discussed. Intensity maps in HeII λ 256, formed at 9 × 104 K, show the chromospheric network. Line intensities of FeX-XIV, formed at temperatures from 1-2 × 106 K, show small-scale bright points and more extended structures. The intensity map of FeVIII shows a transition between the two temperatures. The coronal lines reveal regions of high outflow velocities on the order of 100kms-1 in a compact region and 12kms-1 in an extended region. The presence of such high velocities in the quiet corona is an entirely new and unexpected result. Electron densities derived from density sensitive line ratios of FeXII and XIII are typically 3-20 × 108cm-3. The highest densities are found in bright, compact areas. For the first time, explosive events in the quiet sun have been observed in the extreme-ultraviolet in HeII λ 256 profiles.