dc.contributor.author | Snow, B | |
dc.contributor.author | Botha, GJJ | |
dc.contributor.author | McLaughlin, JA | |
dc.contributor.author | Hillier, AS | |
dc.date.accessioned | 2017-11-02T15:39:18Z | |
dc.date.issued | 2017-10-20 | |
dc.description.abstract | Aims. We aim to investigate the onset of 2D time-dependent magnetic reconnection that is triggered using an external (non-local)
velocity driver located away from, and perpendicular to, an equilibrium Harris current sheet. Previous studies have typically utilised
an internal trigger to initiate reconnection, for example initial conditions centred on the current sheet. Here, an external driver allows
for a more naturalistic trigger as well as the study of the earlier stages of the reconnection start-up process.
Methods. Numerical simulations solving the compressible, resistive magnetohydrodynamics (MHD) equations were performed to
investigate the reconnection onset within different atmospheric layers of the Sun, namely the corona, chromosphere and photosphere.
Results. A reconnecting state is reached for all atmospheric heights considered, with the dominant physics being highly dependent
on atmospheric conditions. The coronal case achieves a sharp rise in electric field (indicative of reconnection) for a range of velocity
drivers. For the chromosphere, we find a larger velocity amplitude is required to trigger reconnection (compared to the corona). For
the photospheric environment, the electric field is highly dependent on the inflow speed; a sharp increase in electric field is obtained
only as the velocity entering the reconnection region approaches the Alfvén speed. Additionally, the role of ambipolar diffusion is
investigated for the chromospheric case and we find that the ambipolar diffusion alters the structure of the current density in the inflow
region.
Conclusions. The rate at which flux enters the reconnection region is controlled by the inflow velocity. This determines all aspects
of the reconnection start-up process, that is, the early onset of reconnection is dominated by the advection term in Ohm’s law in all
atmospheric layers. A lower plasma-β enhances reconnection and creates a large change in the electric field. A high plasma-β hinders
the reconnection, yielding a sharp rise in the electric field only when the velocity flowing into the reconnection region approaches the
local Alfvén speed. | en_GB |
dc.description.sponsorship | The authors acknowledge IDL support provided by STFC.
A. Hillier is supported by his STFC Ernest Rutherford Fellowship grant number
ST/L00397X/2. J.A. McLaughlin acknowledges generous support from the Leverhulme
Trust and this work was funded by a Leverhulme Trust Research Project
Grant: RPG-2015-075. | en_GB |
dc.identifier.citation | Published online 30 October 2017 | en_GB |
dc.identifier.doi | 10.1051/0004-6361/201731214 | |
dc.identifier.uri | http://hdl.handle.net/10871/30121 | |
dc.language.iso | en | en_GB |
dc.publisher | EDP Sciences for European Southern Observatory (ESO) | en_GB |
dc.subject | Magnetohydrodynamics (MHD) | en_GB |
dc.subject | Magnetic fields | en_GB |
dc.subject | Reconnection | en_GB |
dc.subject | Sun: corona | en_GB |
dc.subject | Sun: magnetic fields | en_GB |
dc.title | Onset of 2D magnetic reconnection in the solar photosphere, chromosphere and corona | en_GB |
dc.type | Article | en_GB |
dc.date.available | 2017-11-02T15:39:18Z | |
dc.identifier.issn | 0004-6361 | |
dc.description | This is the author accepted manuscript. The final version is available from EDP Sciences via the DOI in this record. | en_GB |
dc.identifier.journal | Astronomy and Astrophysics | en_GB |