Direct Observations of Magnetic Reconnection Outflow and CME Triggering in a Small Erupting Solar Prominence

摘要

We examine a small prominence eruption that occurred on 2014 May 1 at 01:35UT and was observed by the Interface Region Imaging Spectrometer (IRIS) and theAtmospheric Imaging Assembly (AIA) on the Solar Dynamics Observatory (SDO).Pre- and post-eruption images were taken by the X-Ray Telescope (XRT) onHinode. Pre-eruption, a dome-like structure exists above the prominence, asdemarcated by coronal rain. As the eruption progresses, we find evidence forreconnection between the prominence magnetic field and the overlying field.Fast flows are seen in AIA and IRIS, indicating reconnection outflows.Plane-of-sky flows of ~300 km s$^{-1}$ are observed in the AIA 171 A channelalong a potentially reconnected field line. IRIS detects intermittent fastline-of-sight flows of ~200 km s$^{-1}$ coincident with the AIA flows.Differential emission measure calculations show heating at the origin of thefast flows. Post-eruption XRT images show hot loops probably due toreconfiguration of magnetic fields during the eruption and subsequent heatingof plasma in these loops. Although there is evidence for reconnection above theprominence during the eruption, high spatial resolution images from IRIS revealpotential reconnection sites below the prominence. A height-time analysis ofthe erupting prominence shows a slow initial rise with a velocity of ~0.4 kms$^{-1}$ followed by a rapid acceleration with a final velocity of ~250 kms$^{-1}$. Brightenings in IRIS during the transition between these two phasesindicate the eruption trigger for the fast part of the eruption is likely atether-cutting mechanism rather than a break-out mechanism.