| Issue |
A&A
Volume 602, June 2017
|
|
|---|---|---|
| Article Number | A43 | |
| Number of page(s) | 5 | |
| Section | The Sun | |
| DOI | https://doi.org/10.1051/0004-6361/201629729 | |
| Published online | 02 June 2017 | |
High-frequency waves in the corona due to null points⋆
1 Instituto de Astrofísica de Canarias, 38205 La Laguna, Tenerife, Spain
2 Centre for mathematical Plasma Astrophysics, Department of Mathematics, KU Leuven, Celestijnenlaan 200B, 3001 Leuven, Belgium
e-mail: irantzu.calvosantamaria@kuleuven.be
3 Departamento de Astrofísica, Universidad de La Laguna, 38205 La Laguna, Tenerife, Spain
4 Main Astronomical Observatory, NAS, 03680 Kyiv, Ukraine
Received: 16 September 2016
Accepted: 21 April 2017
This work aims to understand the behavior of non-linear waves in the vicinity of a coronal null point. In previous works we have shown that high-frequency waves are generated in such a magnetic configuration. This paper studies those waves in detail in order to provide a plausible explanation of their generation. We demonstrate that slow magneto-acoustic shock waves generated in the chromosphere propagate through the null point and produce a train of secondary shocks that escape along the field lines. A particular combination of the shock wave speeds generates waves at a frequency of 80 mHz. We speculate that this frequency may be sensitive to the atmospheric parameters in the corona and therefore can be used to probe the structure of this solar layer.
Key words: magnetohydrodynamics (MHD) / plasmas / shock waves / Sun: magnetic fields / Sun: corona
Movies attached to Figs 2 and 4 are available at http://www.aanda.org
© ESO, 2017
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