Fitting of Intensity-Velocity Cross Spectrum using GONG and HMI Oscillation Data
Abstract:The fitting of solar intensity-velocity cross spectrum together
with coherence and intensity-velocity phase difference provides us with
better estimates of the oscillation mode parameters. This also serves
as a diagnostic tool to improve our understanding of the excitation of the
p-modes by convection by estimating the contribution of the solar
backgrounds which may or may not be correlated with the acoustic modes.
Using both GONG and HMI data, we will present our results of fitting four
spectra simultaneously viz. velocity, intensity, the phase difference
and the coherence between the intensity and velocity spectra.
We will compare the mode parameters obtained from a
single-observable and those from cross-spectral fitting method and comment on
the solar cycle variation of mode parameters. We will also
characterize and compare the contribution from different background components.