Heating-Related Flows in Cool Solar Loops
Abstract
The effects of spatial and temporal variations are investigated in the heating of cool-type solar loop models. In contrast to hot loops, these cool loops have temperature gradients that are everywhere shallow and maximum temperatures that are well below 10 K. The results of our numerical simulations show that spatial asymmetries in the energy input to cool loops will produce steady state, end-to-end flows. Velocities exceeding 20 km/s are possible. In no case, however, is the downflowing leg appreciably faster or appreciably brighter than the upflowing leg (at a given temperature), and no significant Doppler shift would be seen from an unresolved loop. Other simulations show that symmetric, but sudden, reductions in the energy input can also produce downflows of large velocity. These flows are transient, and because they arise from cooling of the plasma, the greatest velocities (>4km/s) are restricted to temperatures below 50,000 K. Spatial and temporal heating variations of the types considered here are unable to explain the net redshifts observed in emission lines formed near 500,000 K on the Sun. Keywords: Solar activity; Solar atmosphere; Reprints.
Document Details
- Document Type
- Technical Report
- Publication Date
- May 01, 1988
- Accession Number
- ADA197002
Entities
People
- J. A. Klimchuk
- J. T. Mariska
Organizations
- United States Naval Research Laboratory