Magnetohydrodynamic Waves in a Bounded Inhomogeneous Medium with Prominence-Corona Properties

Abstract

view Abstract Citations (21) References (31) Co-Reads Similar Papers Volume Content Graphics Metrics Export Citation NASA/ADS Magnetohydrodynamic Waves in a Bounded Inhomogeneous Medium with Prominence-Corona Properties Oliver, R. ; Ballester, J. L. Abstract Short- and long-period oscillations in quiescent solar prominences have been abundantly reported during recent years. In this paper, we investigate the magnetoacoustic-gravity modes of vibration of an inhomogeneous medium in which the temperature and density vary smoothly from prominence to coronal values. The differential equations of slow, fast, and Alfvén modes have been solved numerically, and the main properties of these modes have been studied. The perturbations to the plasma pressure, magnetic pressure, magnetic tension, and gravitational forces have been computed because these forces are responsible for the different nature of fast and slow MHD modes. It has been found that motions produced by slow modes are driven by the horizontal component of the pressure gradient, while the main driver of fast modes is the magnetic tension which is practically vertical in most, but not all, cases. As for the association of different modes with different polarizations of the velocity of oscillation, we have found that slow and Alfvén modes present a dominant component in the horizontal plane, in a direction transverse to and along the prominence axis, respectively. However, and contrary to what was found in previous works, some fast modes produce both vertical and horizontal motions. When the Doppler shift of a spectral line is used, this implies that all three MHD modes could be detected in a limb prominence and that only the fast mode could be detected in a filament located in the disk center. No evidence for hybrid, external, and internal modes has been found, which suggests that this subdivision, previously reported in Oliver et al. (1993) and Joarder & Roberts (1992b), disappears when the temperature suffers a smooth transition from prominence to coronal conditions. Publication: The Astrophysical Journal Pub Date: July 1995 DOI: 10.1086/175975 Bibcode: 1995ApJ...448..444O Keywords: MAGNETOHYDRODYNAMICS: MHD; SUN: CORONA; SUN: MAGNETIC FIELDS; SUN: OSCILLATIONS; SUN: PROMINENCES; WAVES full text sources ADS |