AAS 200th meeting, Albuquerque, NM, June 2002
Session 4. Helioseismology and the Solar Interior
Display, Monday, June 3, 2002, 9:20am-6:30pm, SW Exhibit Hall

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[4.10] Simultaneous Velocity-Intensity Spectral and Cross-Spectral Fitting for Helioseismology

C. Barban, F. Hill (NSO)

Helioseismology seeks to infer the properties of the solar interior from the oscillation mode parameters, primarily the frequency. Thus, increasing the precision and accuracy of the mode parameter estimates correspondingly improves our knowledge of the solar interior. The parameters are typically determined by fitting a theoretical profile to the observed Doppler velocity (V) power spectrum, neglecting the information contained in the spectrum of total intensity (I). This information content is demonstrated by the qualitative differences, such as substantial frequency shifts and the sense of the line asymmetry, that are unmistakable in simultaneous V and I spectra. Clearly the physics of the oscillation determining the mode parameters cannot depend on the observed quantity, thus the differences are likely to arise from the excitation mechanism. Further, these differences can be used to derive a more complete and accurate model of the solar oscillations improving the mode parameter estimation and providing new measures of the excitation. Following Severino et al. (2001,ApJ 561,444), we present preliminary results from simultaneously fitting 4 spectra (V and I power, I-V phase difference and I-V coherence spectra) to constrain the theoretical mode profile.

This work is supported by NASA grant NAG5-11703.

The author(s) of this abstract have provided an email address for comments about the abstract: barban@noao.edu

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Bulletin of the American Astronomical Society, 34
© 2002. The American Astronomical Soceity.