arXiv subjects

Sarah Gibson

Publications and source records attributed to Sarah Gibson.

20 records · Page 2Linked to original sources

arXiv2013

Prominence Mass Supply and the Cavity

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 171Å 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.

astro-ph.SR↗

arXiv2013

Diagnosing the Prominence-Cavity Connection

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 (EUV) 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 171Åbandpass. 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 171Åand 193Åbandpasses, however the 193Åemission is a factor of 5 weaker. There is also a strong correlation between structural changes to the prominence as viewed in the He II 304Åbandpass and the enhanced 171Åemission. In that bandpass, the prominence appears to extend several megameters along the 171Åhorn where we observe co-spatial, co-temporal 304Åand 171Åemission 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 under dense because it supplies mass to the over dense prominence.

astro-ph.SR↗