Lessons from SUMMER/SOHO Solar Ultraviolet Spectrograph
Abstract
Our understanding of the high-temperature solar atmosphere is to a large extent based on spectroscopic observations of emission lines and continuum radiation in the vacuum-ultraviolet (VUV) wavelength range of the electromagnetic spectrum. The VUV radiation is produced by transitions of atoms and ions, or to some extent, of molecules. The atomic and ionic emission lines have formation temperatures between 10,000 K and several million Kelvin, representative of the chromosphere, the transition region and the corona. The molecular lines and the continua originate in cooler regions of the Sun. Radiation at VUV wavelengths is strongly absorbed by the Earth's atmosphere and can only be detected with instruments on sounding rockets and spacecraft above the atmosphere. Detailed studies of the spectral radiances together with atomic physics data furnish information on the electron density and temperature of the solar atmosphere, as well as on elemental abundances, whereas Doppler line-shift measurements show bulk plasma motions, turbulence, and ion temperatures. Research in this field will be presented using measurements of the Solar Ultraviolet Measurements of Emitted Radiation (SUMER) instrument on the ESA/NASA Solar and Heliospheric Observatory (SOHO). In addition, the instrumental technique will be briefly introduced as well as the scientific use of the data obtained over a period of ten years.
- Publication:
-
2nd UN/NASA Workshop on International Heliophysical Year and Basic Space Science
- Pub Date:
- November 2006
- Bibcode:
- 2006ihy..workE..30W