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Transition Region Redshifts in Quiet Sun, Coronal Hole, and Active Region Ingolf E. Dammasch Solar Influences Data Analysis Center, Royal Observatory of.

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Presentation on theme: "Transition Region Redshifts in Quiet Sun, Coronal Hole, and Active Region Ingolf E. Dammasch Solar Influences Data Analysis Center, Royal Observatory of."— Presentation transcript:

1 Transition Region Redshifts in Quiet Sun, Coronal Hole, and Active Region Ingolf E. Dammasch Solar Influences Data Analysis Center, Royal Observatory of Belgium, Circular Avenue 3, 1180 Uccle, Brussels, Belgium Uri Feldman Artep Inc., 2922 Excelsior Spring Circle, Ellicott City, Columbia MD 21042, and Space Science Division, Naval Research Laboratory, Washington DC , USA Abstract SUMER, the telescope and spectrograph on SOHO, is able to observe the Sun in several VUV lines and temperature regimes simultaneously. Extended SUMER scans performed on various regions of the solar disk lead to thousands of line profiles per study. These profiles can then be ordered according to radiance, and averaged. Thus, not only the well- known redshifts of chromospheric and transition-region lines are confirmed, but the relationship between the magnitudes of redshift and radiance is also demonstrated. While chromospheric and coronal lines only show redshifts for brighter plasma, transition-region lines show them everywhere on the quiet Sun. In coronal holes and active regions, however, their characteristics become more complicated. This will be described, and some explanations provided. Introduction Wavelength shifts of lines emitted by solar plasmas were reported since the early 1970s. The S082-B normal-incidence spectrometer on Skylab, having a spatial resolution of 2"x60", recorded simultaneously spectral lines spanning the Å range. Since the recorded spectra included relatively narrow (FWHM~0.06Å) chromospheric lines from 1- 2x10 4 K plasmas as well as the wider (FWHM~0.20Å) lower transition region lines of 2x10 4


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