Stability and mode analysis of solar coronal loops using thermodynamic irreversible energy principles

¹ Instituto de Astronomía y Física del Espacio (CONICET-Argentina) e-mail: costa@iafe.uba.ar
² Universidad Nacional de General Sarmiento (UNGS)
³ Departamento de Física (FCEyN-UBA-Argentina)

Received: 14 March 2006
Accepted: 7 July 2006

Abstract

Aims.We study the modes and stability of non-isothermal coronal loop models with different intensity values of the equilibrium magnetic field.

Methods.We use an energy principle obtained via non-equilibrium thermodynamic arguments. The principle is expressed in terms of Hermitian operators and allow to consider together the coupled system of equations: the balance of energy equation and the equation of motion.

Results.We determine modes characterized as long – wavelength disturbances that are present in inhomogeneous media. This character of the system introduces additional difficulties for the stability analysis because the inhomogeneous nature of the medium determines the structure of the disturbance, which is no longer sinusoidal. Moreover, another complication is that we obtain a continuous spectrum of stable modes in addition to the discrete one.

Conclusions.We obtain a unique unstable mode with a characteristic time that is comparable with the characteristic life-time observed for loops. The feasibility of wave-based and flow-based models is examined.