Cosmic-Ray Interactions in the Solar Atmosphere. (arXiv:1910.01186v1 [astro-ph.SR])
<a href="http://arxiv.org/find/astro-ph/1/au:+Hudson_H/0/1/0/all/0/1">Hugh Hudson</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+MacKinnon_A/0/1/0/all/0/1">Alec MacKinnon</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Szydlarski_M/0/1/0/all/0/1">Mikolaj Szydlarski</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Carlsson_M/0/1/0/all/0/1">Mats Carlsson</a>
High-energy particles enter the solar atmosphere from Galactic or solar
coronal sources, producing an “albedo” source from the quiet Sun, now
observable across a wide range of photon energies. The interaction of
high-energy particles in a stellar atmosphere depends essentially upon the
joint variation of the magnetic field and the gas, which heretofore has been
characterized parametrically as P ~ B^alpha with P the gas pressure and B the
magnitude of the magnetic field. We re-examine that parametrization by using a
self-consistent 3D MHD model (Bifrost) and show that this relationship tends to
P ~ B^{2.9+-0.1} based on the visible portions of the sample of open-field flux
tubes in such a model, but with large variations from point to point. This
scatter corresponds to the strong meandering of the open-field flux tubes in
the lower atmosphere, which will have a strong effect on the prediction of the
emission anisotropy (limb brightening). The simulations show that much of the
open flux in coronal holes originates in weak-field regions within the granular
pattern of the convective motions seen in the simulations.
High-energy particles enter the solar atmosphere from Galactic or solar
coronal sources, producing an “albedo” source from the quiet Sun, now
observable across a wide range of photon energies. The interaction of
high-energy particles in a stellar atmosphere depends essentially upon the
joint variation of the magnetic field and the gas, which heretofore has been
characterized parametrically as P ~ B^alpha with P the gas pressure and B the
magnitude of the magnetic field. We re-examine that parametrization by using a
self-consistent 3D MHD model (Bifrost) and show that this relationship tends to
P ~ B^{2.9+-0.1} based on the visible portions of the sample of open-field flux
tubes in such a model, but with large variations from point to point. This
scatter corresponds to the strong meandering of the open-field flux tubes in
the lower atmosphere, which will have a strong effect on the prediction of the
emission anisotropy (limb brightening). The simulations show that much of the
open flux in coronal holes originates in weak-field regions within the granular
pattern of the convective motions seen in the simulations.
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