[Loops] New paper on Active Regions

[Jaume Terradas Calafell]

Dear loop community,
 
Perhaps this group might be interested in an attempt to construct
magnetohydrostatic models of coronal active regions in two dimensions.
The paper has been recently accepted for publication in A&A:
https://arxiv.org/abs/2202.06800

Title: Construction of coronal hole and active region magnetohydrostatic
solutions in two dimensions: Force and energy balance

Authors: Terradas, J.; Soler, R.; R., Oliver; Antolin, P.; Arregui, I.; Luna,
M.; Piantschitsch, I.; Soubrié, E.; L, Ballester J.

Abstract:

Coronal holes and active regions are typical magnetic structures found in the
solar atmosphere. We propose several magnetohydrostatic equilibrium solutions
that are representative of these structures in two dimensions. Our models
include the effect of a finite plasma-beta and gravity, but the distinctive
feature is that we incorporate a thermal structure with properties similar to
those reported by observations. We developed a semi-analytical method to compute
the equilibrium configuration. Using this method, we obtain cold and under-dense
plasma structures in open magnetic fields representing coronal holes, while in
closed magnetic configurations, we achieve the characteristic hot and over-dense
plasma arrangements of active regions. Although coronal holes and active regions
seem to be antagonistic structures, we find that they can be described using a
common thermal structure that depends on the flux function. In addition to the
force balance, the energy balance is included in the constructed models using an
a posteriori approach. From the two-dimensional computation of thermal
conduction and radiative losses in our models, we infer the required heating
function to achieve energy equilibrium. We find that the temperature dependence
on height is an important parameter that may prevent the system from
accomplishing thermal balance at certain spatial locations. The implications of
these results are discussed in detail.

Comments, suggestions and criticisms are welcome.
 
Kind regards,
Jaume
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