0000000000200728
AUTHOR
Duncan H. Mackay
showing 12 related works from this author
Hydrogen non-equilibrium ionisation effects in coronal mass ejections
2020
This research has received funding from the Science and Technology Facilities Council (UK) through the consolidated grant ST/N000609/1 and the European Research Council (ERC) under the European Union Horizon 2020 research and innovation program (grant agreement No. 647214). D.H.M. would like to thank both the UK STFC and the ERC (Synergy grant: WHOLE SUN, grant Agreement No. 810218) for financial support. D.H.M. and P.P. would like to thank STFC for IAA funding under grant number SMC1-XAS012. This work used the DiRAC@Durham facility man-aged by the Institute for Computational Cosmology on behalf of the STFC DiRAC HPC Facility (www.dirac.ac.uk. The equipment was funded by BEIS capital fundin…
Effect of gravitational stratification on the propagation of a CME
2013
Our aim is to study the role of gravitational stratification on the propagation of CMEs. In particular, we assess how it influences the speed and shape of CMEs and under what conditions the flux rope ejection becomes a CME or when it is quenched. We ran a set of MHD simulations that adopt an eruptive initial magnetic configuration that has already been shown to be suitable for a flux rope ejection. We varied the temperature of the backgroud corona and the intensity of the initial magnetic field to tune the gravitational stratification and the amount of ejected magnetic flux. We used an automatic technique to track the expansion and the propagation of the magnetic flux rope in the MHD simula…
Magnetohydrodynamic study on the effect of the gravity stratification on flux rope ejections
2013
Context. Coronal mass ejections (CMEs) are the most violent phenomenon found on the Sun. One model that explains their occurrence is the flux rope ejection model. A magnetic flux rope is ejected from the solar corona and reaches the interplanetary space where it interacts with the pre-existing magnetic fields and plasma. Both gravity and the stratification of the corona affect the early evolution of the flux rope. Aims. Our aim is to study the role of gravitational stratification on the propagation of CMEs. In particular, we assess how it influences the speed and shape of CMEs and under what conditions the flux rope ejection becomes a CME or when it is quenched. Methods. We ran a set of MHD…
Simulating AIA observations of a flux rope ejection
2014
D.H.M. would like to thank STFC, the Leverhulme Trust and the European Commission’s Seventh Framework Programme (FP7/2007-2013) for their financial support. P.P. would like to thank the European Commission’s Seventh Framework Programme (FP7/2007-2013) under grant agreement SWIFF (project 263340, http://www.swiff.eu) and STFC for financial support. These results were obtained in the framework of the projects GOA/2009-009 (KU Leuven), G.0729.11 (FWO-Vlaanderen) and C 90347 (ESA Prodex 9). The research leading to these results has also received funding from the European Commission’s Seventh Framework Programme (FP7/2007-2013) under the grant agreements SOLSPANET (project No. 269299, http:// ww…
Origin and Ion Charge State Evolution of Solar Wind Transients during 4 – 7 August 2011
2016
We present study of the complex event consisting of several solar wind transients detected by Advanced Composition Explorer (ACE) on 4 -- 7 August 2011, that caused a geomagnetic storm with Dst$=-$110 nT. The supposed coronal sources -- three flares and coronal mass ejections (CMEs) occurred on 2 -- 4 August 2011 in the active region (AR) 11261. To investigate the solar origin and formation of these transients we studied kinematic and thermodynamic properties of the expanding coronal structures using the Solar Dynamics Observatory/Atmospheric Imaging Assembly (SDO/AIA) EUV images and the differential emission measure (DEM) diagnostics. The Helioseismic and Magnetic Imager (HMI) magnetic fie…
A prospective new diagnostic technique for distinguishing eruptive and noneruptive active regions
2019
This research has received funding from the Science and Technology Facilities Council (UK) through the consolidated grant ST/N000609/1 and the European Research Council (ERC) under the European Union Horizon 2020 research and innovation program (grant agreement No. 647214). This work used the DiRAC@Durham facility managed by the Institute for Computational Cosmology on behalf of the STFC DiRAC HPC Facility (www.dirac.ac.uk). The equipment was funded by BEIS capital funding via STFC capital grants ST/P002293/1, ST/R002371/1, and ST/S002502/1, Durham University and STFC operations grant ST/R000832/1. DiRAC is part of the National e-Infrastructure. S.L.Y. would like to acknowledge STFC for sup…
Numerical Simulations of a Flux Rope Ejection
2015
Coronal mass ejections (CMEs) are the most violent phenomena observed on the Sun. One of the most successful models to explain CMEs is the flux rope ejection model, where a magnetic flux rope is expelled from the solar corona after a long phase along which the flux rope stays in equilibrium while magnetic energy is being accumulated. However, still many questions are outstanding on the detailed mechanism of the ejection and observations continuously provide new data to interpret and put in the context. Currently, extreme ultraviolet (EUV) images from the Atmospheric Imaging Assembly (AIA) on board the Solar Dynamic Observatory (SDO) are providing new insights into the early phase of CME evo…
Magnetohydrodynamic simulations of the ejection of a magnetic flux rope
2013
Context. Coronal mass ejections (CME's) are one of the most violent phenomena found on the Sun. One model to explain their occurrence is the flux rope ejection model. In this model, magnetic flux ropes form slowly over time periods of days to weeks. They then lose equilibrium and are ejected from the solar corona over a few hours. The contrasting time scales of formation and ejection pose a serious problem for numerical simulations. Aims: We simulate the whole life span of a flux rope from slow formation to rapid ejection and investigate whether magnetic flux ropes formed from a continuous magnetic field distribution, during a quasi-static evolution, can erupt to produce a CME. Methods: To …
A new technique for observationally derived boundary conditions for space weather
2018
This research has received funding from the European Research Council (ERC) under the European Union’s Horizon 2020 research and innovation programme (grant agreement No 647214). D.H.M. would like to thank STFC and the Leverhulme Trust for their financial support. ARY was supported by STFC consortium grant ST/N000781/1 to the universities of Dundee and Durham. Context. In recent years, space weather research has focused on developing modelling techniques to predict the arrival time and properties of coronal mass ejections (CMEs) at the Earth. The aim of this paper is to propose a new modelling technique suitable for the next generation of Space Weather predictive tools that is both efficie…
Future capabilities of CME polarimetric 3D reconstructions with the METIS instrument: A numerical test
2015
D.H.M. would like to thank STFC and the Leverhulme Trust for their financial support. P.P. would like to thank STFC and the Leverhulme Trust. The computational work for this paper was carried out on the joint STFC and SFC (SRIF) funded cluster at the University of St Andrews (Scotland, UK). Context. Understanding the 3D structure of coronal mass ejections (CMEs) is crucial for understanding the nature and origin of solar eruptions. However, owing to the optical thinness of the solar corona we can only observe the line of sight integrated emission. As a consequence the resulting projection effects hide the true 3D structure of CMEs. To derive information on the 3D structure of CMEs from whit…
A space weather tool for identifying eruptive active regions
2019
Funding: UK Science and Technology Facilities Council (UK) through the consolidated grant ST/N000609/1 and the European Research Council (ERC) under the European Union Horizon 2020 research and innovation program (grant agreement No. 647214); UK STFC via the Consolidated Grant SMC1/YST025 and SMC1/YST037 (S.L.Y.); UK STFC and the ERC (SynergyGrant: WHOLE SUN, Grant Agreement No. 810218) for financial support (DHM). One of the main goals of solar physics is the timely identification of eruptive active regions. Space missions such as Solar Orbiter or future Space Weather forecasting missions would largely benefit from this achievement.Our aim is to produce a relatively simple technique that c…
Determining the source and eruption dynamics of a stealth CME using NLFFF modelling and MHD simulations
2021
Coronal mass ejections (CMEs) that exhibit weak or no eruption signatures in the low corona, known as stealth CMEs, are problematic as upon arrival at Earth they can lead to geomagnetic disturbances that were not predicted by space weather forecasters. We investigate the origin and eruption of a stealth event that occurred on 2015 January 3 that was responsible for a strong geomagnetic storm upon its arrival at Earth. To simulate the coronal magnetic field and plasma parameters of the eruption we use a coupled approach. This approach combines an evolutionary nonlinear force-free field model of the global corona with a MHD simulation. The combined simulation approach accurately reproduces th…