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

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.

arXiv commentAccepted for publication in A&A

References in corpus (17)

• Observing the fine structure of loops through high resolution spectroscopic observations of coronal rain with the CRISP instrument at the Swedish Solar Telescope
• A Systematic Survey of High Temperature Emission in Solar Active Regions
• Evidence for Widespread Cooling in an Active Region Observed with the SDO Atmospheric Imaging Assembly
• Patterns of Nanoflare Storm Heating Exhibited by an Active Region Observed with SDO/AIA
• Similarities and Differences between Coronal Holes and the Quiet Sun: Are Loop Statistics the Key?
• On the occurrence of thermal non-equilibrium in coronal loops
• The Role of Asymmetries in Thermal Non-Equilibrium
• The Distinction Between Thermal Nonequilibrium and Thermal Instability
• Signatures of Steady Heating in Time Lag Analysis of Coronal Emission
• Systematic Construction of Exact 2-D MHD Equilibria with Steady, Compressible Flow in Cartesian Geometry and Uniform Gravity
• The role of asymmetries in coronal rain formation during thermal non-equilibrium cycles
• 2D MHD modelling of compressible and heated coronal loops obtained via nonlinear separation of variables and compared to TRACE and SoHO observations
• Numerical Simulation of Coronal Waves Interacting with Coronal Holes: II. Dependence on Alfvén Speed Inside the Coronal Hole
• Numerical Simulation of Coronal Waves Interacting with Coronal Holes: III. Dependence on Initial Amplitude of the Incoming Wave
• Analytical Three-dimensional Magnetohydrostatic Equilibrium Solutions for Magnetic Field Extrapolation Allowing a Transition from Non-force-free to Force-free Magnetic Fields
• Geometrical properties of the interaction between oblique incoming coronal waves and coronal holes
• A new method for estimating global coronal wave properties from their interaction with solar coronal holes

Cited by in corpus (2)

• Standing Sausage Perturbations in Solar Coronal Slabs with Continuous Transverse Density Profiles: cutoff wavenumbers, evanescent eigenmodes, and oscillatory continuum
• Three-dimensional solar active region magnetohydrostatic models and their stability using Euler potentials