Volume 644, December 2020
|Number of page(s)||6|
|Section||The Sun and the Heliosphere|
|Published online||25 November 2020|
Seismological constraints on the solar coronal heating function
Centre for Fusion, Space and Astrophysics, Department of Physics, University of Warwick, CV4 7AL Coventry, UK
2 Institute of Solar-Terrestrial Physics SB RAS, Irkutsk 664033, Russia
3 St. Petersburg Branch, Special Astrophysical Observatory, Russian Academy of Sciences, 196140 St. Petersburg, Russia
Accepted: 7 October 2020
Aims. The hot solar corona exists because of the balance between radiative and conductive cooling and some counteracting heating mechanism that remains one of the major puzzles in solar physics.
Methods. The coronal thermal equilibrium is perturbed by magnetoacoustic waves, which are abundantly present in the corona, causing a misbalance between the heating and cooling rates. As a consequence of this misbalance, the wave experiences a back-reaction, either losing or gaining energy from the energy supply that heats the plasma, at timescales comparable to the wave period.
Results. In particular, the plasma can be subject to wave-induced instability or over-stability, depending on the specific choice of the coronal heating function. In the unstable case, the coronal thermal equilibrium would be violently destroyed, which does not allow for the existence of long-lived plasma structures typical for the corona. Based on this, we constrained the coronal heating function using observations of slow magnetoacoustic waves in various coronal plasma structures.
Key words: Sun: oscillations / waves / radiation mechanisms: thermal
© ESO 2020
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