Corrections of Sun-as-a-star p-mode frequencies for effects of the solar cycle

TL;DR

This paper details methods to correct Sun-as-a-star p-mode frequencies for solar cycle effects, enabling consistent comparisons across different observation periods and improving solar interior modeling.

Contribution

It introduces three correction techniques for p-mode frequencies affected by the solar cycle, including adjustments for activity levels, mode properties, and observational limitations.

Findings

Developed correction procedures for solar p-mode frequencies.

Enabled activity-independent solar interior inversions.

Produced a definitive set of Sun-as-a-star frequencies.

Abstract

Solar p-mode frequencies vary with solar activity. It is important to take this into account when comparing the frequencies observed from epochs that span different regions of the solar cycle. We present details of how to correct observed p-mode frequencies for the effects of the solar cycle. We describe three types of correction. The first allows mode frequencies to be corrected to a nominal activity level, such as the canonical quiet-Sun level. The second accounts for the effect on the observed mode frequencies, powers, and damping rates of the continually varying solar cycle and is pertinent to frequencies obtained from very long data sets. The third corrects for Sun-as-a-star observations not seeing all components of the modes. Suitable combinations of the three correction procedures allow the frequencies obtained from different sets of data to be compared and enable activity-independent inversions of the solar interior. As an example of how to apply the corrections we describe those used to produce a set of definitive Sun-as-a-star frequencies.