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Three-dimensional magnetic reconnection in a collapsing coronal loop system  

Shane Maloney   Submitted: 2018-06-26 11:08

Magnetic reconnection is believed to be the primary mechanism by which non-potential energy stored in coronal magnetic fields is rapidly released during solar eruptive events. Unfortunately, owing to the small spatial scales on which reconnection is thought to occur, it is not directly observable in the solar corona. However, larger scale processes, such as associated inflow and outflow, and signatures of accelerated particles have been put forward as evidence of reconnection. Using a combination of observations we explore the origin of a persistent Type I radio source that accompanies a coronal X-shaped structure during its passage across the disk. Of particular interest is the time range around a partial collapse of the structure that is associated with inflow, outflow, and signatures of particle acceleration. Imaging radio observations from the Nançay Radioheliograph were used to localise the radio source. Solar Dynamics Observatory (SDO) AIA extreme ultraviolet (EUV) observations from the same time period were analysed, looking for evidence of inflows and outflows. Further mpole magnetic reconstructions using SDO HMI observations allowed the magnetic connectivity associated with the radio source to be determined. The Type I radio source was well aligned with a magnetic separator identified in the extrapolations. During the partial col- lapse, gradual (1 km s-1) and fast (5 km s-1) inflow phases and fast (30 km s-1) and rapid (80-100 km s-1) outflow phases were observed, resulting in an estimated reconnection rate of ∼0.06. The radio source brightening and dimming was found to be co-temporal with increased soft x-ray emission in both Reuven Ramaty High Energy Solar Spectroscopic Imager (RHESSI) and Geostationary Operational Environmental Satellite (GOES). Conclusions. We interpret the brightening and dimming of the radio emission as evidence for accelerated electrons in the reconnection region responding to a gradual fall and rapid rise in electric drift velocity, in response to the inflowing and outflowing field lines. These results present a comprehensive example of 3D null-point reconnection.

Authors: Aidan M. O'Flannagain, Shane A. Maloney, Peter T. Gallagher, Philippa Browning, Jose Refojo
Projects: GOES X-rays,RHESSI,SDO-AIA,SDO-HMI

Publication Status: Accepted
Last Modified: 2018-06-26 11:57
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STEREO Direct Imaging of a CME-driven Shock to 0.5AU  

Shane Maloney   Submitted: 2011-06-08 10:49

This abstract was corrupted following database problems and is being recovered. It will be restored as quickly as possible. Any questions, please send them to Alisdair. Sorry for any incovenience.


Authors: Shane A. Maloney and Peter T. Gallagher
Projects: STEREO

Publication Status: ApjL (in press)
Last Modified: 2011-06-09 08:58
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Solar Wind Drag and the Kinematics of Interplanetary Coronal Mass Ejections  

Shane Maloney   Submitted: 2010-10-03 19:10

Coronal mass ejections (CMEs) are large-scale ejections of plasma and magnetic field from the solar corona, which propagate through interplanetary space at velocities of sim100-2500 km s-1. Although plane-of-sky coronagraph measurements have provided some insight into their kinematics near the Sun (<32~R_odot), it is still unclear what forces govern their evolution during both their early acceleration and later propagation. Here, we use the dual perspectives of the Solar TErrestrial RElations Observatory (STEREO) spacecrafts to derive the three-dimensional kinematics of CMEs over a range of heliocentric distances (sim2-250,Rodot). We find evidence for solar wind (SW) drag-forces acting in interplanetary space, with a fast CME decelerated and a slow CME accelerated towards typical SW velocities. We also find that the fast CME showed linear (delta=1) dependence on the velocity difference between the CME and the SW, while the slow CME showed a quadratic (delta=2) dependence. The differing forms of drag for the two CMEs indicate the forces and thus mechanism responsible for there acceleration may be different.

Authors: Shane, A. Maloney, Peter, T. Gallagher
Projects: STEREO

Publication Status: In press
Last Modified: 2010-10-04 18:07
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Three-dimensional magnetic reconnection in a collapsing coronal loop system
STEREO Direct Imaging of a CME-driven Shock to 0.5AU
Solar Wind Drag and the Kinematics of Interplanetary Coronal Mass Ejections

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