Coordinated observations of the quiet Sun transition region using SUMER spectra, TRACE images and MDI magnetograms
Title | Coordinated observations of the quiet Sun transition region using SUMER spectra, TRACE images and MDI magnetograms |
Publication Type | Journal Article |
Year of Publication | 2001 |
Authors | Innes, D. E. |
Journal | Astronomy and Astrophysics |
Volume | 378 |
Pagination | 1067-1077 |
Date Published | Nov |
Abstract | The relationship between the transition region ultraviolet emission and the underlying magnetic field is explored through a detailed analysis of SUMER SI IV line profiles, TRACE C IV, continuum and 171 Å intensities, and MDI high resolution magnetic field measurements. The observations track a narrow area of quiet Sun near disk center over a period of 3 hours. Highly variable emission is found throughout. The most dramatic line Doppler shift and brightness variations come from a region of complex field evolution. The brightenings sometimes have faint elongated extensions in the TRACE C IV images. In most events with high Doppler shifts, the SI IV line wing reveals plasma flow 1-2 min before the line core brightens which suggests that plasma acceleration precedes plasma compression and/or heating. SImultaneous measurement of transition region densities using O IV line ratios imply large density fluctuations in the transition region plasma. There is an indication of waves of compression and rarefaction crossing the spectrometer's field-of-view. The waves' speed across the solar surface is between 20-40 $\backslash$kms, and the compression may be as high as 10. In space-time images density fluctuations are much more prevalent and conspicuous than brightenings. In several cases the waves seem to start at the position of SI IV brightenings. |
DOI | 10.1051/0004-6361:20011177 |
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