Observed Redshifts in O V and Downflows in the Solar Transition Region
Abstract
Spectrograms from HRTS are used to find an average net redshift of the O V lines at 1218 and 1371 A at all locations extending from disk center to solar limb. The observed shift in O V is compared with measurements of the O IV line at 1401 A and the Si IV line at 1402 A. Large variations in the shift are found along the instrument slit. Blueshifts are also observed with the sites of the largest upflow located in the sunspot umbrae and in a quiet region close to an active region. The present result could put new constraints on numerical models of flows in the solar transition region and will also be of importance for modeling stellar atmospheres. The spatial variation of line-of-sight velocities in the O V line at 1371A and the SI IV line at 1402 A is illustrated.
- Publication:
-
The Astrophysical Journal
- Pub Date:
- May 1993
- DOI:
- 10.1086/172633
- Bibcode:
- 1993ApJ...408..735B
- Keywords:
-
- Doppler Effect;
- Magnetohydrodynamic Flow;
- Oxygen Spectra;
- Red Shift;
- Solar Corona;
- Ultraviolet Radiation;
- Hubble Space Telescope;
- Skylab Program;
- Spectrographs;
- Umbras;
- Solar Physics;
- SUN: UV RADIATION;
- SUN: TRANSITION REGION;
- SUN: CORONA