Estimating the p-mode frequencies of the solar twin 18 Sco

TL;DR

This paper uses high-precision spectroscopic data and advanced spectral analysis to estimate and identify oscillation frequencies in the solar twin 18 Sco, providing a foundation for detailed seismic modeling.

Contribution

It introduces a method combining MCMC and MAP optimization to reliably extract and identify p-mode frequencies in 18 Sco from HARPS data, advancing asteroseismology of solar twins.

Findings

Estimated 52 frequencies with MCMC

Identified 21 reliable pulsation modes

Provided seismic indicators for 18 Sco

Abstract

Solar twins have been a focus of attention for more than a decade, because their structure is extremely close to that of the Sun. Today, thanks to high-precision spectrometers, it is possible to use asteroseismology to probe their interiors. Our goal is to use time series obtained from the HARPS spectrometer to extract the oscillation frequencies of 18 Sco, the brightest solar twin. We used the tools of spectral analysis to estimate these quantities. We estimate 52 frequencies using an MCMC algorithm. After examination of their probability densities and comparison with results from direct MAP optimization, we obtain a minimal set of 21 reliable modes. The identification of each pulsation mode is straightforwardly accomplished by comparing to the well-established solar pulsation modes. We also derived some basic seismic indicators using these values. These results offer a good basis to start a detailed seismic analysis of 18 Sco using stellar models.