Forward modelling to determine the observational signatures of propagating slow waves for TRACE, SoHO/CDS, and Hinode/EIS
School of Mathematics and Statistics, University of St Andrews, North Haugh, St Andrews, Fife, KY16 9SS, Scotland, UK e-mail: firstname.lastname@example.org
Accepted: 27 November 2008
Context. The propagation and damping of slow MHD waves in the solar atmosphere are investigated by numerical simulations and forward modelling, with particular emphasis placed on waves with periodicities of the order of five minutes.
Aims. We extend a coronal model by adding an equilibrium temperature gradient allowing study of wave propagation from the transition region to the corona.
Methods. A 1D model is used that includes gravitational stratification and damping by thermal conduction, optically thin radiation, and compressive viscosity. Forward modelling of the simulation results, for both uniform and non-uniform equilibrium temperature profiles, is undertaken to establish the observational consequences of the physical processes involved for TRACE, SoHO/CDS, and Hinode/EIS.
Results. The presence of thermal conduction causes a phase shift between the wave velocity, energy, and density. This shift may be observable by comparing Doppler velocity and intensity observations. Phase shifts are also seen between intensity observations by different instruments and between different spectral lines. This is an observational effect that arises due to the forward modelling process in which observations are synthesised, but it is not seen in the simulation results. Oscillations from the transition region are found to dominate the coronal emission for TRACE 171 Å by nearly two orders of magnitude.
Key words: Sun: oscillations / Sun: corona / Sun: transition region
© ESO, 2009