Thermal Stability of Coronal Loops - Part Two - Symmetric Modes and Constraints on the Heating Mechanism

Details Thermal Stability of Coronal Loops - Part Two - Symmetric Modes and Constraints on the Heating Mechanism Thermal Stability of Coronal Loops - Part Two - Symmetric Modes and Constraints on the Heating Mechanism

Feb 1985

adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=1985apj...289..834m&link_type=abstract

Astrophysical Journal, Vol.289, NO.2/FEB15, P. 834, 1985

Astronomy and Astrophysics

Astrophysics

15

Scientific paper

The nature of the coronal heating mechanism is examined in the light of the general analysis of thermal stability of coronal loops developed in Paper I. In Paper I we showed that: (i) a loop whose heating rate depends on temperature and pressure is neutrally stable to antisymmetric perturbations, and (ii) the symmetric "generalized isobaric" mode is stable if the heating rate per atom is constant. Here we demonstrate that, if the coronal heating mechanism depends on temperature and pressure, a necessary condition on the pressure dependence of the heating mechanism must be satisfied for loop stability. Identifying the generalized isobaric mode with chromospheric evaporation, we derive an (approximate) necessary and sufficient condition. Loosely speaking, the heating rate per atom must not increase with pressure faster than a power between zero and one, whose precise value depends on the temperature dependence of the heating mechanism. An explicit dependence on column depth of the heating mechanism is destabilizing if it causes the heating rate to decrease with height, and vice versa. A loop is unstable to antisymmetric perturbations if the heating rate tends to decrease with height because of its column depth dependence. The effect on stability of the heating mechanism may be understood by considering the change in the average coronal heating rate produced by evaporation or condensation at the loop footpoints. If the addition of evaporated chromospheric material to the corona increases the heating rate more than it increases the coronal radiation rate, an excess conductive flux is produced, leading to more evaporation, and hence instability.

Affiliated with

Also associated with

No associations

Rating

Thermal Stability of Coronal Loops - Part Two - Symmetric Modes and Constraints on the Heating Mechanism does not yet have a rating. At this time, there are no reviews or comments for this scientific paper.

If you have personal experience with Thermal Stability of Coronal Loops - Part Two - Symmetric Modes and Constraints on the Heating Mechanism, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Thermal Stability of Coronal Loops - Part Two - Symmetric Modes and Constraints on the Heating Mechanism will most certainly appreciate the feedback.

Rate now

Comments { 0 }

Profile ID: LFWR-SCP-O-1591225