Measurements of extreme-ultraviolet emission-line profiles near the solar limb

Abstract

view Abstract Citations (119) References (23) Co-Reads Similar Papers Volume Content Graphics Metrics Export Citation NASA/ADS Measurements of extreme-ultraviolet emission-line profiles near the solar limb. Mariska, J. T. ; Feldman, U. ; Doschek, G. A. Abstract Line profiles of optically thin extreme-ultraviolet emission lines observed in a quiet sun region at positions within and above the white-light limb with the NRL slit spectrograph (S082-B) on Skylab are discussed. Absolute line intensities and full widths at half-maximum are presented for lines formed over the temperature range from about 10,000 to 22,000 K. The line intensities are compared with the predictions of simple atmospheric models consisting of a spicule component and a thin spherically symmetric or network models, but can be explained by assuming that the emission arises from spicule-like inhomogeneities. Random mass-motion velocities are calculated. The velocity increases with increasing temperature of line formation. Near the limb and above about 4000 K the calculated velocity is consistent with the predictions of a constant acoustic flux passing through the transition zone. For the ions formed at temperatures not less than about 63,000 K, the velocity is found to increase with increasing height above the white-light limb. Publication: The Astrophysical Journal Pub Date: December 1978 DOI: 10.1086/156652 Bibcode: 1978ApJ...226..698M Keywords: Astronomical Spectroscopy; Chromosphere; Far Ultraviolet Radiation; Solar Limb; Solar Spectra; Atmospheric Models; Emission Spectra; Line Spectra; Mass Flow; Skylab Program; Solar Temperature; Spectral Line Width; Spectrographs; Spicules; Velocity Measurement; Solar Physics; Extreme UV:Solar Spectrum; Line Profiles:Solar Spectrum full text sources ADS |