Initial Results from Fitting Resolved Modes using HMI Intensity Observations

TL;DR

This paper presents initial results from analyzing HMI intensity observations to extract solar oscillation modes, comparing these with velocity-based measurements to evaluate the effectiveness of the new intensity data processing.

Contribution

It introduces a new analysis of HMI intensity data for helioseismology, applying a state-of-the-art fitting method to spherical harmonic coefficients.

Findings

Mode characteristics are consistent between intensity and velocity data.

First 360 days of intensity observations processed and analyzed.

Initial results demonstrate feasibility of using intensity data for helioseismology.

Abstract

The HMI project recently started processing the continuum intensity images following global helioseismology procedures similar to those used to process the velocity images. The spatial decomposition of these images has produced time series of spherical harmonic coefficients for degrees up to $\ell=300$, using a different apodization than the one used for velocity observations. The first 360 days of observations were processed and made available. In this paper I present initial results from fitting these time series using my state of the art fitting methodology and compare the derived mode characteristics to those estimated using co-eval velocity observations.