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dc.contributor.authorFyfe, Lianne
dc.contributor.authorHowson, Thomas Alexander
dc.contributor.authorDe Moortel, Ineke
dc.date.accessioned2020-09-18T14:30:09Z
dc.date.available2020-09-18T14:30:09Z
dc.date.issued2020-11
dc.identifier.citationFyfe , L , Howson , T A & De Moortel , I 2020 , ' Forward modelling of MHD Waves in braided magnetic fields ' , Astronomy & Astrophysics , vol. 643 , A86 . https://doi.org/10.1051/0004-6361/202038945en
dc.identifier.issn0004-6361
dc.identifier.otherPURE: 270210419
dc.identifier.otherPURE UUID: e866e308-c6c8-495b-93db-390d67a9fdff
dc.identifier.otherScopus: 85095969020
dc.identifier.otherWOS: 000591273300005
dc.identifier.otherORCID: /0000-0002-1452-9330/work/98487482
dc.identifier.otherORCID: /0000-0002-4895-6277/work/98488073
dc.identifier.urihttp://hdl.handle.net/10023/20646
dc.descriptionFunding: UK Science and Technology Facilities Council (consolidated grants ST/N000609/1 and ST/S000402/1) and the European Union Horizon 2020 research and innovation programme (grant agreement No.647214). IDM acknowledges support from the Research Council of Norway through its Centres of Excellence scheme, project number 262622.en
dc.description.abstractAims. We investigate synthetic observational signatures generated from numerical models of transverse waves propagating in complex (braided) magnetic fields. Methods. We consider two simulations with different levels of magnetic field braiding and impose periodic, transverse velocity perturbations at the lower boundary. As the waves reflect off the top boundary, a complex pattern of wave interference occurs.Weapply the forward modelling code FoMo and analyse the synthetic emission data. We examine line intensity, Doppler shifts and kinetic energy along several line-of-sight (LOS) angles. Results. The Doppler shift perturbations clearly showed the presence of the transverse (Alfvénic) waves. However, in the total intensity (and running difference), the waves are less easily observed for more complex magnetic fields andmay be indistinguishablefrom background noise. Depending on the LOS angle, the observable signatures of the waves reflect some of the magnetic field braiding, particularly when multiple emission lines are available, although it is not possible to deduce the actual level ofcomplexity. In the more braided simulation, signatures of phase mixing can be identified. We highlight possible ambiguities in the interpretation of the wave modes based on the synthetic emission signatures. Conclusions. Most of the observables discussed in this article behave in the manner expected, given knowledge of the evolution of the parameters in the 3D simulations. Nevertheless, some intriguing observational signatures are present. Identifying regions of magnetic field complexity is somewhat possiblewhen waves are present although even then, simultaneous spectroscopic imaging from different lines is important to identify these locations. Care needs to be taken when interpreting signatures in the intensity and Doppler velocities as torsional motions as in our setup, such signatures were a consequence of the complex nature of the magnetic field rather than real torsional waves. Finally, we investigated the kinetic energy, estimated from the Doppler velocities, which is highly dependent on the polarisation of the wave, complexity of the background field and the LOS angles.
dc.format.extent15
dc.language.isoeng
dc.relation.ispartofAstronomy & Astrophysicsen
dc.rightsCopyright © 2020 ESO. This work has been made available online in accordance with publisher policies or with permission. Permission for further reuse of this content should be sought from the publisher or the rights holder. This is the author created accepted manuscript following peer review and may differ slightly from the final published version. The final published version of this work is available at http://www.aanda.org/.en
dc.subjectSun: coronaen
dc.subjectSun: magnetic fieldsen
dc.subjectSun: oscillationsen
dc.subjectMagnetohydrodyanmics (MHD)en
dc.subjectQB Astronomyen
dc.subjectQC Physicsen
dc.subjectNDASen
dc.subject.lccQBen
dc.subject.lccQCen
dc.titleForward modelling of MHD Waves in braided magnetic fieldsen
dc.typeJournal articleen
dc.description.versionPostprinten
dc.contributor.institutionUniversity of St Andrews.Applied Mathematicsen
dc.identifier.doihttps://doi.org/10.1051/0004-6361/202038945
dc.description.statusPeer revieweden


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