Frank Q. Orrall

Systematic radial flows in the chromosphere, transition region, and corona of the quiet Sun

An observational study of the systematic radial flows representative of the quiet Suns chromosphere, transition region, and corona is presented. A sounding rocket experiment (1987 July 27) obtained high-resolution EUV spectra along a solar diameter with spatial resolution of 20″ × 20″. The center-to-limb behavior of four representative lines (Si II λ1533, Fe II λ1563, C IV λ1548, Ne VIII λ770) formed at different heights in the solar atmosphere is discussed

The systematic radial downflow in the transition region of the quiet sun from limb-to-limb observations of the C IV resonance lines

This paper presents absolute velocities of C IV 1548, 1550 nm measured as a function of position along the solar equator, which was free of both active regions and coronal holes, and uniformly representative of the quiet sun. These observations were made with moderate spatial resolution (18 arcsec) using an EUV spectrometer dedicated to measuring absolute wavelengths (velocities) by direct comparison with a platinum spectrum generated on board the sounding rocket. On the assumption that systematic horizontal motions cancel statistically so that the line-of-sight velocities approach zero at the limb, a net radial downflow of 7.5 + or - 1.0 km/sec was found. The assumption was tested using the wavelength reference and found to be valid within the absolute accuracy of the rest wavelengths of the C IV lines.