Search results for "Sun: oscillations"
showing 9 items of 9 documents
Contribution of phase-mixing of Alfvén waves to coronal heating in multi-harmonic loop oscillations
2018
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’s Horizon 2020 research and innovation program ( grant agreement No. 647214). This work is supported by the European Research Council under the SeismoSun Research Project No. 321141 (DJP). This project has received funding from the European Research Council (ERC) under the European Union’s Horizon 2020 research and innovation programme (grant agreement No 724326). This work used the DiRAC Data Centric system at Durham University, operated by the Institute for Computational Cosmology on behalf o…
Contribution of mode coupling and phase-mixing of Alfv\'en waves to coronal heating
2017
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) and from the UK Science and Technology Facilities Council. This work used the DiRAC Data Centric system at Durham University, operated by the Institute for Computational Cosmology on behalf of the STFC DiRAC HPC Facility (www.dirac.ac.uk. This equipment was funded by a BIS National E-infrastructure capital grant ST/K00042X/1, STFC capital grant ST/K00087X/1, DiRAC Operations grant ST/K003267/1 and Durham University. Context. Phase-mixing of Alfvén waves in the solar corona has been identified as one possible candid…
Oscillations on Width and Intensity of Slender Ca ii H Fibrils from Sunrise/SuFI
2017
R. Gafeira et. al.
Propagating Alfvén waves in open structures with random structuring
2022
Funding: The research leading to these results has received funding from the UK Science and Technology Facilities Council (consolidated grant ST/N000609/1), the European Union Horizon 2020 research and innovation programme (grant agreement No. 647214). IDM received funding from the Research Council of Norway through its Centres of Excellence scheme, project number 262622. We consider the behaviour of Alfvén waves propagating in a medium with random density perturbations. The imposed density perturbations have a broadband spectrum and their characteristic spatial scale may be defined according to the peak in the spectrum. The interaction of the boundary driven Alfvén waves with the medium ge…
Transverse Oscillations in Slender Ca II H Fibrils Observed with Sunrise/SuFI
2016
S. Jafarzadeh et. al.
MHD simulations of the in situ generation of kink and sausage waves in the solar corona by collision of dense plasma clumps
2019
Funding: This research has received funding from the UK Science and Technology Facilities Council (Consolidated Grant ST/K000950/1) and the European Union Horizon 2020 research and innovation programme (grant agreement No. 647214). P.A. acknowledges funding from his STFC Ernest Rutherford Fellowship (No. ST/R004285/1). This research was supported by the Research Council of Norway through its Centres of Excellence scheme, project number 262622. Context. Magnetohydrodynamic (MHD) waves are ubiquitous in the solar corona where the highly structured magnetic fields provide efficient wave guides for their propagation. While MHD waves have been observed originating from lower layers of the solar …
Chromospheric evaporation and phase mixing of Alfvén waves in coronal loops
2020
Phase mixing of Alfv\'en waves has been studied extensively as a possible coronal heating mechanism but without the full thermodynamic consequences considered self-consistently. It has been argued that in some cases, the thermodynamic feedback of the heating could substantially affect the transverse density gradient and even inhibit the phase mixing process. In this paper, we use MHD simulations with the appropriate thermodynamical terms included to quantify the evaporation following heating by phase mixing of Alfv\'en waves in a coronal loop and the effect of this evaporation on the transverse density profile. The numerical simulations were performed using the Lare2D code. We set up a 2D l…
Effect of coronal loop structure on wave heating through phase mixing
2020
Context. The mechanism(s) behind coronal heating still elude(s) direct observation and modelling of viable theoretical processes and the subsequent effect on coronal structures is one of the key tools available to assess possible heating mechanisms. Wave heating via the phase mixing of magnetohydrodynamic (MHD) transverse waves has been proposed as a possible way to convert magnetic energy into thermal energy, but MHD models increasingly suggest this is not an efficient enough mechanism. Aims. We modelled heating by phase mixing transverse MHD waves in various configurations in order to investigate whether certain circumstances can enhance the heating sufficiently to sustain the million deg…
Contribution of observed multi frequency spectrum of Alfvén waves to coronal heating
2019
Context. Whilst there are observational indications that transverse magnetohydrodynamic (MHD) waves carry enough energy to maintain the thermal structure of the solar corona, it is not clear whether such energy can be efficiently and effectively converted into heating. Phase-mixing of Alfvén waves is considered a candidate mechanism, as it can develop transverse gradient where magnetic energy can be converted into thermal energy. However, phase-mixing is a process that crucially depends on the amplitude and period of the transverse oscillations, and only recently have we obtained a complete measurement of the power spectrum for transverse oscillations in the corona. Aims. We aim to investig…