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See detailEstimating the p-mode frequencies of the solar twin 18 Scorpii
Bazot, M.; Campante, T.L.; Chaplin, W.J. et al

in Astronomy and Astrophysics (2012), 544

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 ... [more ▼]

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. [less ▲]

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See detailThe radius and mass of the close solar twin 18 Scorpii derived from asteroseismology and interferometry
Bazot, Michaël; Ireland, M. J.; Huber, D. et al

in Astronomy and Astrophysics (2011), 526

The growing interest in solar twins is motivated by the possibility of comparing them directly to the Sun. To carry on this kind of analysis, we need to know their physical characteristics with precision ... [more ▼]

The growing interest in solar twins is motivated by the possibility of comparing them directly to the Sun. To carry on this kind of analysis, we need to know their physical characteristics with precision. Our first objective is to use asteroseismology and interferometry on the brightest of them: 18 Sco. We observed the star during 12 nights with HARPS for seismology and used the PAVO beam-combiner at CHARA for interferometry. An average large frequency separation 134.4 ± 0.3 μHz and angular and linear radiuses of 0.6759 ± 0.0062 mas and 1.010 ± 0.009 Rsun were estimated. We used these values to derive the mass of the star, 1.02 ± 0.03 Msun. [less ▲]

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