Turbulence in a Coronal Loop Excited by Photospheric Motions
Photospheric motions are believed to be the source of coronal heating and of velocity fluctuations detected in the solar corona. A numerical model, based on the shell technique applied on reduced magnetohydrodynamics equations, is used to represent energy injection due to footpoint motions, storage...
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doaj-05189026f0e04cfc8c6512dec6dcbe3a2020-11-25T02:27:48ZengMDPI AGAtmosphere2073-44332020-04-011140940910.3390/atmos11040409Turbulence in a Coronal Loop Excited by Photospheric MotionsGiuseppina Nigro0Francesco Malara1Antonio Vecchio2Leonardo Primavera3Francesca Di Mare4Vincenzo Carbone5Pierluigi Veltri6Dipartimento di Fisica, Università della Calabria, via P. Bucci, 87036 Rende, ItalyDipartimento di Fisica, Università della Calabria, via P. Bucci, 87036 Rende, ItalyRadboud Radio Lab, Department of Astrophysics/IMAPP-Radboud University, P.O. Box 9010, 6500GL Nijmegen, The NetherlandsDipartimento di Fisica, Università della Calabria, via P. Bucci, 87036 Rende, ItalyDepartment of Physics, University of Oslo, 1048 Blindern, 0316 Oslo, NorwayDipartimento di Fisica, Università della Calabria, via P. Bucci, 87036 Rende, ItalyDipartimento di Fisica, Università della Calabria, via P. Bucci, 87036 Rende, ItalyPhotospheric motions are believed to be the source of coronal heating and of velocity fluctuations detected in the solar corona. A numerical model, based on the shell technique applied on reduced magnetohydrodynamics equations, is used to represent energy injection due to footpoint motions, storage and dissipation of energy in a coronal loop. Motions at the loop bases are simulated by random signals whose frequency-wavenumber spectrum reproduces features of photospheric motions: the <i>p</i>-mode peak and the low-frequency continuum. Results indicate that a turbulent state develops, dominated by magnetic energy, where dissipation takes place in an intermittent fashion. The nonlinear cascade is mainly controlled by velocity fluctuations, where resonant modes are dominant at high frequencies. Low frequency fluctuations present a power-law spectra and a bump at <i>p</i>-mode frequency; similar features are observed in velocity spectra detected in the corona. For typical loop parameters the energy input flux is comparable with that necessary to heat the quiet-Sun corona.https://www.mdpi.com/2073-4433/11/4/409solar coronaturbulencenumerical modeling |
collection |
DOAJ |
language |
English |
format |
Article |
sources |
DOAJ |
author |
Giuseppina Nigro Francesco Malara Antonio Vecchio Leonardo Primavera Francesca Di Mare Vincenzo Carbone Pierluigi Veltri |
spellingShingle |
Giuseppina Nigro Francesco Malara Antonio Vecchio Leonardo Primavera Francesca Di Mare Vincenzo Carbone Pierluigi Veltri Turbulence in a Coronal Loop Excited by Photospheric Motions Atmosphere solar corona turbulence numerical modeling |
author_facet |
Giuseppina Nigro Francesco Malara Antonio Vecchio Leonardo Primavera Francesca Di Mare Vincenzo Carbone Pierluigi Veltri |
author_sort |
Giuseppina Nigro |
title |
Turbulence in a Coronal Loop Excited by Photospheric Motions |
title_short |
Turbulence in a Coronal Loop Excited by Photospheric Motions |
title_full |
Turbulence in a Coronal Loop Excited by Photospheric Motions |
title_fullStr |
Turbulence in a Coronal Loop Excited by Photospheric Motions |
title_full_unstemmed |
Turbulence in a Coronal Loop Excited by Photospheric Motions |
title_sort |
turbulence in a coronal loop excited by photospheric motions |
publisher |
MDPI AG |
series |
Atmosphere |
issn |
2073-4433 |
publishDate |
2020-04-01 |
description |
Photospheric motions are believed to be the source of coronal heating and of velocity fluctuations detected in the solar corona. A numerical model, based on the shell technique applied on reduced magnetohydrodynamics equations, is used to represent energy injection due to footpoint motions, storage and dissipation of energy in a coronal loop. Motions at the loop bases are simulated by random signals whose frequency-wavenumber spectrum reproduces features of photospheric motions: the <i>p</i>-mode peak and the low-frequency continuum. Results indicate that a turbulent state develops, dominated by magnetic energy, where dissipation takes place in an intermittent fashion. The nonlinear cascade is mainly controlled by velocity fluctuations, where resonant modes are dominant at high frequencies. Low frequency fluctuations present a power-law spectra and a bump at <i>p</i>-mode frequency; similar features are observed in velocity spectra detected in the corona. For typical loop parameters the energy input flux is comparable with that necessary to heat the quiet-Sun corona. |
topic |
solar corona turbulence numerical modeling |
url |
https://www.mdpi.com/2073-4433/11/4/409 |
work_keys_str_mv |
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