C

Abstract

Prominences and cavities are ubiquitously observed together, but the physical link between these disparate structures has not been established. We address this issue by using dynamic emission in the extreme ultraviolet to probe the connections of these structures. The SDO/AIA observations show that the cavity exhibits excessive emission variability compared to the surrounding quiet-Sun streamer, particularly in the 171 Å bandpass. We find that this dynamic emission takes the form of coherent loop-like brightening structures which emanate from the prominence into the central cavity. The geometry of these structures, dubbed prominence horns, generally mimics the curvature of the cavity boundary. We use a space-time statistical analysis of two cavities in multiple AIA bandpasses to constrain the energetic properties of 45 horns. In general, we find there is a positive correlation between the light curves of the horns in the 171 Å and 193 Å bandpasses; however, the 193 Å emission is a factor of five weaker. There is also a strong correlation between structural changes to the prominence as viewed in the He ii 304 Å bandpass and the enhanced 171 Å emission. In that bandpass, the prominence appears to extend several megameters along the 171 Å horn where we observe co-spatial, co-temporal 304 Å and 171 Å emission dynamics. We present these observations as evidence of the magnetic and energetic connection between the prominence and the cavity. Further modeling work is necessary to explain the physical source and consequences of these events, particularly in the context of the traditional paradigm: the cavity is underdense because it supplies mass to the overdense prominence.