Dynamics of the quiescent solar corona

A model for the quiescent, inhomogeneous solar corona is developed, based upon the concept of loop structures as the basic structural element of the corona. The results, which are compared with observations obtained by the S-054 Skylab X-ray telescope, show that (a) hydrostatic solutions are stable only if the temperature maximum is located at the top of loop structures, and the deposition scale length of the coronal heating mechanism is comparable with (or larger than) the loop scale size; (b) the loop temperature (approx.T/sub max/), pressure p, and size L are related by the expression T/sub max/approx.1.4 x 10/sup 3/(pL)/sup 1/3/, a relation which contains no free parameters; (c) coronal heating models based upon the coronal magnetic field (e.g., Alfven mode dissipation and coronal current heating) are consistent with the loop model, while acoustic mode damping is not.In accordance with these results, we propose a new model of the corona in which the quiescent X-ray corona represents a metastable equilibrium state. Thus, fluctuations in the local heating rate are shown to lead to dynamically unstable states within loops. These may be identified with transient loop brightenings seen in X-rays; with relatively cool coronal loop structures seen in EUV emission lines,more » which have been reported to extend to heights larger than the imputed pressure scale height and may be associated with downflows of plasma; and with the formation of quiescent prominences within loop structures.« less