Sizes of quiet Sun transition region structures

¹ Research Center for Astronomy and Applied Mathematics, Academy of Athens, Greece e-mail: edara@cc.uoa.gr
² Kiepenheuer-Institut für Sonnenphysik, Schöneckstr. 6, 79104 Freiburg, Germany e-mail: peter@kis.uni-freiburg.de

Corresponding author: C. Gontikakis, cgontik@cc.uoa.gr

Received: 26 September 2002
Accepted: 16 June 2003

Abstract

We studied the morphology of the transition region of the quiet Sun, with data obtained by the Solar Ultraviolet Measurements of Emitted Radiation spectrometer (SUMER) and the Extreme-Ultraviolet Imaging Telescope (EIT), in September 1996. We analyzed lines emitted in the chromosphere, the low transition region and the low corona. We computed the mean autocorrelation function for the radiance images in order to estimate the characteristic size of the features present in the transition region. Moreover, we calculated autocorrelation functions for the dopplergrams and line width images deduced from the SUMER data. In addition to the line core of the C iv line, we investigated a broader tail component, whose origin is still unclear. We found that the size of the bright radiance features is always larger than the size of the structures of the dopplergrams and Doppler widths, at any altitude. The network features seem to diminish at a temperature around 10⁵ K, due to the thermodynamic properties of the transition region. The mean size of the structures of the tail component radiance is smaller than the one of the core radiance.