Hα Doppler Brightening and Lyman-α Doppler Dimming in Moving Hα Prominences
Abstract
We consider the effect that coherent motion has on the observed brightness of moving clouds above the photosphere. We find that steady state clouds (constant Ne and Te) that are moving perpendicular to the line of sight will appear brighter in Hα for speeds between 8 and 100 km/sec and dimmer for speeds greater than 135 km/sec. The brightening and dimming are due to apparent Doppler shifts of the respective Hα absorption and the Lyman-α emission profiles `seen' by the absorption profile of the moving cloud.
- Publication:
-
Solar Physics
- Pub Date:
- September 1970
- DOI:
- 10.1007/BF00240170
- Bibcode:
- 1970SoPh...14..147H
- Keywords:
-
- Flare;
- Optical Depth;
- Coherent Motion;
- Brightness Variation;
- Eruptive Prominence