Emissions ‘froides’ dans la couronne solaire
- Cite this article as:
- Leroy, JL. Sol Phys (1972) 25: 413. doi:10.1007/BF00192338
Prominences have been photographed through a coronagraph and an Hα Lyot filter with long exposure times. Faint Hα emissions are often detected down to the threshold 2 × 10-6 times of the Sun's brightness; they show definite structures but their relations to the low-level ordinary prominences are not very clear. Estimates are given for the density and thickness of such cool regions.