Establish stationary MHD-shock identification and branch classification

Establish whether the X-/cell-like brightness morphology observed in Events 9 and 12 corresponds to stationary MHD shocks, and classify any confirmed transition as a slow, fast, or compound MHD-shock branch using independent plasma-state and characteristic-speed closure.

Background

Events 9 and 12 exhibit oppositely inclined fronts, repeated X-like ridge intersections, cell-like spacing, and expansion-stable outward order. These observations support a shock-cell morphology, but the paper distinguishes that image-level result from the stronger claim that the nodes are stationary MHD shocks.

The available total- and polarized-brightness data do not provide a diagnostic-independent upstream/downstream plasma jump. Establishing stationarity and identifying a slow, fast, or compound branch would require repeated localization of the transition radius, independent plasma states, magnetic-field and temperature constraints, the normal flow or shock speed, characteristic-speed estimates, and Rankine–Hugoniot consistency.

References

The result is therefore two-tiered: the shock-cell pattern is an observed morphological result, while stationary-shock identification and slow/fast/compound MHD classification remain open rather than excluded.

— Where Do Periodic Density Structures Acquire Coherence? A Low-Coronal Resonator Candidate and a 12-Event STEREO/SECCHI Transfer Test  (2608.22670 - Podladchikova, 24 Aug 2026) in Section 4.4, “Shock-cell morphology is present; MHD classification remains open”