  A prevalent but untested paradigm is often used to describe the
prominence-cavity system: the cavity is under-dense because it is evacuated by
supplying mass to the condensed prominence. The thermal non-equilibrium (TNE)
model of prominence formation offers a theoretical framework to predict the
thermodynamic evolution of the prominence and the surrounding corona. We
examine the evidence for a prominence-cavity connection by comparing the TNE
model with diagnostics of dynamic extreme ultraviolet emission (EUV)
surrounding the prominence, specifically prominence horns. Horns are correlated
extensions of prominence plasma and coronal plasma which appear to connect the
prominence and cavity. The TNE model predicts that large-scale brightenings
will occur in the SDO/AIA 171\AA\ bandpass near the prominence that are
associated with the cooling phase of condensation formation. In our
simulations, variations in the magnitude of footpoint heating lead to
variations in the duration, spatial scale, and temporal offset between emission
enhancements in the other EUV bandpasses. While these predictions match well a
subset of the horn observations, the range of variations in the observed
structures is not captured by the model. We discuss the implications of our
one-dimensional loop simulations for the three-dimensional time-averaged
equilibrium in the prominence and the cavity. Evidence suggests that horns are
likely caused by condensing prominence plasma, but the larger question of
whether this process produces a density-depleted cavity requires a more tightly
constrained model of heating and better knowledge of the associated magnetic
structure.
