Downflows in coronal loops
Abstract
The existence of the solar wind requires a net outflow of material at all depths in the solar atmosphere. Thus, the observation of a prevalent downflow at temperatures near 105 K1,2 presents a considerable challenge. Two classes of flow models have been suggested, each involving flow along closed magnetic-field lines that extend above the chromosphere into the hotter transition region and corona. Type-(l) models3,4,5 assume unidirectional equilibrium flows along field lines and rely on asymmetry in the flow and plasma properties to produce an apparent downflow. Type-(2) models2,6, by comparison, assume a series of episodic upflows and subsequent downflows along each line of force and rely on asymmetry in the plasma properties and flow durations to produce a statistically prevalent downflow. Here I argue that observational evidence strongly suggests that both types of flow are present but that type-(2) flow is predominant.
- Publication:
-
Nature
- Pub Date:
- June 1987
- DOI:
- 10.1038/327685a0
- Bibcode:
- 1987Natur.327..685A
- Keywords:
-
- Coronal Loops;
- Flow Distribution;
- Magnetohydrodynamic Flow;
- Solar Magnetic Field;
- Magnetic Field Configurations;
- Solar Atmosphere;
- Solar Wind;
- Solar Physics