The energy balance and pressure in the solar transition zone for network and active region features

The pressure and energy balance in the solar transition zone are determined for about 125 network and active region features from new high spectral (0.06 A) and spatial (1'') resolution extreme-ultraviolet spectra. New plasma diagnostics consisting of Si III line intensity ratios are used...

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Veröffentlicht in:Astrophys. J.; (United States) 1979-10, Vol.233, p.741
Hauptverfasser: Nicolas, K. R., Bartoe, J.-D. F., Brueckner, G. E., Vanhoosier, M. E.
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Sprache:eng
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Zusammenfassung:The pressure and energy balance in the solar transition zone are determined for about 125 network and active region features from new high spectral (0.06 A) and spatial (1'') resolution extreme-ultraviolet spectra. New plasma diagnostics consisting of Si III line intensity ratios are used to find the electron density N, and pressure P/sub e/ near 3.5 x 10/sup 4/ K, the temperature where Si III is most abundant. The observed Si III line intensity ratios, R (1301/1312) and R (1301/1296), are compared with theoretical calculations for these ratios as functions of density and temperature. From this comparison, electron densities ranging from 2 x 10/sup 10/ cm/sup -3/ at 2000 km above the limb to 10 /sup 12/ cm/sup -3/ in an active region are derived. The energy losses due to radiation are compared with two energy source terms, conductive flux and turbulent energy dissipation. The radiative losses are proportional only to P/sub e//sup 2/. However, the divergence of the conductive flux is a function of the fill factor a and the average temperature gradient in the line of sight , and the turbulent energy dissipation is a function of a and P/sub e/. P/sub e/ and can be found from plasma diagnostics and emission line intensities, but values of a must be derived by assuming the spatial extent of the transition zone plasma along the line of sight.In an extreme case a=1 for a plane-parallel homogeneous transition zone, and the divergence of the conductive flux and turbulent energy dissipation balance the radiative losses.
ISSN:0004-637X
1538-4357
DOI:10.1086/157436