- Title
- Non-thermal line broadening due to braiding-induced turbulence in solar coronal loops
- Creator
- Pontin, D. I.; Peter, H.; Chitta, L. P.
- Relation
- Astronomy and Astrophysics Vol. 639, Issue 1 July 2020, no. 639
- Relation
- uon-N488521-CPE275586061
- Publisher
- EDP Sciences
- Resource Type
- journal article
- Date
- 2020
- Description
- Aims: Emission line profiles from solar coronal loops exhibit properties that are unexplained by current models. We investigate the non-thermal broadening associated with plasma heating in coronal loops that is induced by magnetic field line braiding. Methods: We describe the coronal loop by a 3D magnetohydrodynamic model of the turbulent decay of an initially-braided magnetic field. From this, we synthesised the Fe XII line at 193 Å that forms around 1.5 MK. Results: The key features of current observations of extreme ultraviolet (UV) lines from the corona are reproduced in the synthesised spectra: (i) Typical non-thermal widths range from 15 to 20 km s−1. (ii) The widths are approximately independent of the size of the field of view. (iii) There is a correlation between the line intensity and non-thermal broadening. (iv) Spectra are found to be non-Gaussian, with enhanced power in the wings of the order of 10–20%. Conclusions: Our model provides an explanation that self-consistently connects the heating process to the observed non-thermal line broadening. The non-Gaussian nature of the spectra is a consequence of the non-Gaussian nature of the underlying velocity fluctuations, which is interpreted as a signature of intermittency in the turbulence.
- Subject
- sun: corona; line: profiles; magnetohydrodynamics (MHD); turbulence; magnetic reconnection
- Identifier
- http://hdl.handle.net/1959.13/1439767
- Identifier
- uon:41028
- Identifier
- ISSN:0004-6361
- Language
- eng
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