HR: 1330h
AN: SP13A-05    [Abstracts]
TI: Theoretical Predictions of Sunquake Waves
AU: * Podesta, J
EM: jpodesta@solar.stanford.edu
AF: NASA Goddard Space Flight Center, Greenbelt, Maryland 20771,
AB: The propagation of ring waves across the surface of the sun in response to a flare initiated sunquake is modeled using Euler's equations of fluid dynamics. The solar convection zone is modeled as a plane parallel gas layer in hydrostatic equilibrium with an adiabatic temperature gradient. Small amplitude perturbations about this equilibrium state are described by the linearized Euler equations for an inviscid compressible fluid (the actual convective motions on the sun are neglected for the purpose of calculating the wave motions). The normal modes of oscillation of this solar model, which can be expressed in terms of generalized Laguerre polynomials, are used to construct the solution of an initial value problem for the linearized equations of motion. Assuming that the form of the initial velocity pulse is Gaussian, the solutions for the vertical velocity at the solar surface are computed as a function of time and compared to the observational data for the sunquake event of 9 July 1996. Model calculations of the position of the wave packet as a function of time predict arrival times that are a few minutes ahead of the observations (1 to 5 minutes) for the range of distances between 10 and 120 Mm from the point of impact or, equivalently, for the range of times between 15 and 50 minutes after the assumed time of impact of the flare ejecta (or shock wave) on the solar surface. It is concluded that the model is in good agreement with the observational data with an error of roughly 10% or 20%.
DE: 7500 SOLAR PHYSICS, ASTROPHYSICS, AND ASTRONOMY
DE: 7519 Flares
DE: 7522 Helioseismology
DE: 7529 Photosphere
SC: Solar Physics Division - AAS [SP]
MN: 2005 Joint Assembly