Transition region and coronal structuring

Abstract

In this paper we examine regions of internetwork, network and bright network emission, observed in the quiet Sun with the Coronal Diagnostic Spectrometer (cds) onboard SoHO. The slopes of the emission measure distributions, between 5.4 <= log T_e <= 6.0, are found to differ in each region, suggesting the presence of different atmospheric structures. From an analysis of emission area the network is shown to have two populations of structures, a low transition region group and a coronal group. Using mdi magnetograms the bright network emission is shown to originate from regions of strong magnetic field composed of bipolar loops and unipolar funnels, that extend from the low transition region up to the corona. Up to 30% of all radiative losses between 5.7 <= log T_e <= 6.3 are found to come from these continuous bright network structures. Cross-sectional areas calculated from redshift values suggest that the area expansion seen in the bright network emission is the result of flux tube expansion into the corona, accompanied by either a downflow or upflow of material.