Time damping of linear non-adiabatic magnetohydrodynamic waves in an unbounded plasma with solar coronal properties

¹ Departament de Matemàtiques i Informàtica, Universitat de les Illes Balears, 07122 Palma de Mallorca, Spain
² Departament de Física, Universitat de les Illes Balears, 07122 Palma de Mallorca, Spain e-mail: marc.carbonell@uib.es;ramon.oliver@uib.es

Corresponding author: J. L. Ballester, dfsjlb0@uib.es

Received: 29 July 2003
Accepted: 14 November 2003

Abstract

In this paper, we study the time damping of magnetoacoustic waves when the adiabaticity assumption is removed by means of an energy equation which includes optically thin radiative losses, thermal conduction and heating. For the sake of simplicity, this study has been done for a homogeneous, isothermal and unbounded medium permeated by a uniform magnetic field, with physical properties akin to those of the corona, the prominence-corona transition region (PCTR) and prominences. In some PCTR regimes and in the coronal regime wave instabilities appear, which prevents the computation of the damping time and the damping per period for part of the wavenumber interval considered. Furthermore, except for one of the PCTR regimes, in the rest of the regimes the apparition of those instabilities depends on the heating mechanism considered. Also, for the same heating mechanism, the behaviour of the damping time for the different considered regimes changes significantly when going from very small to very large wavenumbers and, in all the regimes, it becomes almost constant for very large wavenumbers.