Investigating bi-directional flows in a quiescent prominence using MAST Ca II 8542 Å line scan observations

Abstract

Quiescent prominences are large magnetic structures hosting cool plasma in the surrounding million-degree solar corona. Prominences host different flows that may distort magnetic field lines, which may lead to magnetic reconnection inside the prominence body. In this study, we investigate bi-directional flow patches in aquiescent prominence. The investigation included the analysis of velocities inline-of-sight (LOS) and plane-of-sky (POS) of the prominence, complemented with intensity at different spectral positions of the Ca II 8542˚ Aline. The LOS velocities were obtained using Gaussian fitting to the observed Ca II spectra, whereas the POS velocities were derived from a position-time diagram along a vertical slit in the region of interest (ROI). Complementary to Ca II 8542˚ Aline scans, EUV intensity images from AIA/SDO were analyzed to investigate the multi-thermal nature of the observed bi-directional flows. Out of two ROIs, in the first ROI, a large central patch of bi-directional flow was present initially that merged with other patches and disappeared approximately 30 minutes from the beginning, followed by the generation of another set of patches. Co-spatial with diverging LOS motions of order 10km s−1 associated with patch dynamics, POS motions of similar order were also observed in the ROI. Diverging intensity enhancements indifferent AIA channels, indicating a multi-thermal 19 nature of bi-directional flows, were observed co-spatially with diverging flows in the POS. Similar dynamics were observed in the second ROI. Bi-directional flow patches and the associated dynamics in LOS and POS may be related to magnetic reconnection inside the prominence.