A Coronal Spectrum in the 500–1610 A Wavelength Range Recorded at a Height of 21,000 Kilometers above the West Solar Limb by the SUMER Instrument on Solar and Heliospheric Observatory

Publisher Website
Google Scholar
Abstract
We present a solar coronal spectrum recorded by the extreme UV spectrometer SUMER on the Solar and Heliospheric Observatory. The spectrum was taken between 21:28 UT on 1996 June 25 and 02:47 UT on 1996 June 26, at a height of 21,000 km above the west equatorial limb with the slit oriented in the north-south direction. At the time of the observations the Sun was rather quiet, and the west limb appeared "devoid of any activity." The spectrum, which covers the 500-1610 Å wavelength range, originates from plasmas with temperatures ranging between 1.5 × 104 and 1.5 × 106 K. Identification of lines originating from different temperature regimes is facilitated by the appearance of their intensity along the 300'' long slit. Well over 800 lines have been found, many of which were not previously observed. We present the entire spectrum and discuss line identifications. A table of the wavelengths of lines observed, with their identifications and peak intensities, is provided. Although we have identified lines previously detected in laboratory plasmas and a number of new lines not previously observed, over 40% of the SUMER lines remain unidentified. Among the newly detected lines, some have a potential as plasma density diagnostics.