𝔖 Bobbio Scriptorium
✦   LIBER   ✦

Thermal instability of coronal neutral sheets and the formation of quiescent prominences

✍ Scribed by M. A. Raadu; M. Kuperus


Publisher
Springer
Year
1973
Tongue
English
Weight
948 KB
Volume
28
Category
Article
ISSN
0038-0938

No coin nor oath required. For personal study only.

✦ Synopsis


It is argued that the quiscent prominences are a natural consequence of the formation and thermal instability of current sheets in the corona. Thus observation and theory of prominences can give vital information on the presence of currents and the topology of magnetic fields in the corona. Conversely by developing the theory of the structure and evolution of current sheets under coronal conditions we can attempt to gain a comprehensive understanding of the structure, evolution, and mass and energy balance of quiescent prominences. A stability analysis for coronal material permeated by a vertical magnetic field rooted in the photosphere, indicates that a condensation will take the form of a thin vertical wedge of cool matter. The development of a finite condensation is followed and it is shown that photospheric line tying is only important in the initial stages. A perturbation analysis of vertical motions at the neutral sheet shows that thermal instability can lead to overstable oscillations. Cooling of coronal material can lead to both upward and downward mass motions, and gravitational energy release is important to the thermal balance of prominences. Relevant optical and radio observations are discussed. Synoptic observations of the development of active regions and magnetic fields are needed to test the basic hypothesis of the formation of prominences from neutral sheets.


πŸ“œ SIMILAR VOLUMES


The structure of coronal arcades and the
✍ E. R. Priest; E. A. Smith πŸ“‚ Article πŸ“… 1979 πŸ› Springer 🌐 English βš– 869 KB

The temperature and density are obtained for coronal plasma in thermal and hydrostatic equilibrium and located in a force-free magnetic arcade. The isotherms are found to be inclined to the magnetic field lines and so care should be taken in inferring the magnetic structure from observed emission.