HR: 14:30h
AN: SP23C-04    [Abstracts]
TI: Modelling the Interaction of p-modes With Sunspots
AU: * Crouch, A D
EM: ash@ASTRO.UMontreal.CA
AF: Département de Physique, Université de Montréal, C.P. 6128, Succursale Centre-ville, Montréal, QC H3C3J7 Canada
AU: * Crouch, A D
EM: ash@ASTRO.UMontreal.CA
AF: Centre for Stellar and Planetary Astrophysics, Monash University, Wellington Road, Clayton, Melbourne, VIC 3800 Australia
AU: Cally, P S
EM: paul.cally@sci.monash.edu.au
AF: Centre for Stellar and Planetary Astrophysics, Monash University, Wellington Road, Clayton, Melbourne, VIC 3800 Australia
AU: Charbonneau, P
EM: paulchar@ASTRO.UMontreal.CA
AF: Département de Physique, Université de Montréal, C.P. 6128, Succursale Centre-ville, Montréal, QC H3C3J7 Canada
AU: Desjardins, M
EM: michele@ASTRO.UMontreal.CA
AF: Département de Physique, Université de Montréal, C.P. 6128, Succursale Centre-ville, Montréal, QC H3C3J7 Canada
AB: Sunspots absorb energy from and shift the phase of f- and p-modes incident upon them. One promising absorption mechanism is partial conversion to slow magnetoacoustic-gravity waves (and Alfvén waves), which guide energy along the magnetic field away from the acoustic cavity. Recent mode conversion calculations by Cally, Crouch, and Braun have shown that simple sunspot models with non-vertical magnetic fields can produce ample absorption to explain the observations, along with phase shift predictions that agree remarkably well with the Hankel analysis data. In this investigation, we further test the mode conversion hypothesis. We use a realistic solar model that accounts for both the magnetic and thermal influences associated with a sunspot. Our model has several adjustable parameters - the field strength and inclination can vary (crudely) across the spot. We employ a genetic algorithm to adjust these parameters to optimize the agreement between the model predictions and the observations. At this stage, our model is too simple to perform quantitative forward modelling. However, the genetic algorithm allows us to rigorously test the model. We will discuss the results of this testing in detail. Broadly speaking, our findings are consistent with those of Cally, Crouch, and Braun: the predicted phase shifts are in excellent agreement with the Hankel analysis data, and the corresponding absorption coefficients are generally ample to explain the observations. While there remain several uncertainties, our results further verify that mode conversion is a significant process in sunspot acoustics.
DE: 7500 SOLAR PHYSICS, ASTROPHYSICS, AND ASTRONOMY
DE: 7522 Helioseismology
DE: 7524 Magnetic fields
SC: Solar Physics Division - AAS [SP]
MN: 2005 Joint Assembly