Farside helioseismology with Sun-as-a-star data: the solar cycle as seen with 7-day-long BiSON timeseries

TL;DR

This study analyzes 32 years of Sun-as-a-star helioseismic data to reveal how solar activity influences p-mode frequencies, demonstrating the potential to detect activity on the Sun's far side and in other stars using short observation periods.

Contribution

It introduces a method to detect activity-related frequency shifts from short time series, including the Sun's far side, advancing helioseismic and asteroseismic research.

Findings

Mode frequencies depend on solar activity.

Frequency sensitivity varies with activity level.

Far-side activity influences observed frequency shifts.

Abstract

We present results from fitting $p$-mode spectra derived from 7-d segments of Sun-as-a-star helioseismic observations from the Birmingham Solar Oscillations Network covering 32 yr. The results show a clear dependence of the mode frequencies on solar activity, and the frequency dependence of the sensitivity to activity can also be seen. Because we use data segments that cover less than half of a solar rotation, we are able to test for the effect of activity on the solar far side. By fitting with a model that takes into account activity on the far side of the Sun, we show that the frequency shifts are sensitive to activity from the whole Sun, not just the side facing the observer. Our results suggest that there is potential to investigate activity-related asteroseismic frequency shifts in solar-like oscillators using short time series of observations.