Bibcode
Santamaria, I. C.; Khomenko, E.; Collados, M.
Bibliographical reference
Astronomy and Astrophysics, Volume 577, id.A70, 13 pp.
Advertised on:
5
2015
Journal
Citations
36
Refereed citations
36
Description
Aims: The aim of this work is to study the energy transport by
means of Magnetohydrodynamic (MHD) waves propagating in quiet-Sun
magnetic topology from layers below the surface to the corona. Upwardly
propagating waves find obstacles, such as the equipartition layer with
plasma β = 1, the transition region, and null points, and they get
transmitted, converted, reflected, and refracted. Understanding the
mechanisms by which MHD waves can reach the corona can give us
information about the solar atmosphere and the magnetic structures. Methods: We carried out two-dimensional numerical simulations of wave
propagation in a magnetic field structure that consists of two vertical
flux tubes with the same polarity separated by an arcade-shaped magnetic
field. This configuration contains a null point in the corona, which
significantly modifies the behavior of the waves as they pass near it.
Results: We describe in detail the wave propagation through the
atmosphere under different driving conditions. We also present the
spatial distribution of the mean acoustic and magnetic energy fluxes for
the cases where these calculations are possible, as well as the spatial
distribution of the dominant frequencies in the whole domain.
Conclusions: We conclude that the energy reaches the corona preferably
along almost vertical magnetic fields, that is, inside the vertical flux
tubes. This energy is acoustic in nature. Most of the magnetic energy
stays concentrated below the transition region owing to the refraction
of the magnetic waves and the continuous conversion of acoustic-like
waves into fast magnetic waves in the equipartition layer located in the
photosphere where plasma β = 1. However, part of the magnetic
energy reaches the low corona when propagating in the region where the
arcades are located, but waves are sent back downward into the lower
atmosphere at the null-point surroundings. This phenomenon, together
with the reflection and refraction of waves in the TR and the lower
turning point, act as a re-feeding of the atmosphere, which keeps
oscillating during all the simulation time even if a driver with a
single pulse was used as initial perturbation. In the frequency
distribution, we find that high frequency waves can reach the corona
outside the vertical flux tubes.
Movies related to Figs. 3, 7, and 11 are available in electronic form at
http://www.aanda.org
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