Coronal Loop Widths and Pressure Scale Heights

The scale heights of stratification and the widths of steady solar coronalloops exhibit properties unexplained by standard theory: observed scale heightsare often much greater than static theory predicts, while the nearly-constantwidths of loop emission signatures defy theoretical expectations for large fluxtubes in stratified media. In this work we relate the cross-sectional profileof a coronal flux tube to its density scale height in steady-state plasma flowregimes. Steady flows may shorten or lengthen the scale height according to howthe tube cross-sectional area varies with arclength. In a near-potential coronathe flux tubes are expected to be sufficiently expansive in many active regionsfor scale heights to be increased by steady flows. On the other hand, caseswhere scale lengths are actually increased to observed sizes form a small partof the solution space, close to regimes where density profiles reverse.Therefore, although steady flows are the only steady process known to becapable of extending scale heights significantly, they are not expected to benot responsible for the majority of extended active region scale heights