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

M. Bazot, T. L. Campante, W. J. Chaplin, H. Carfantan, T. R. Bedding, X. Dumusque, A. M. Broomhall, P. Petit, S. Théado, V. Van Grootel, T. Arentoft, M. Castro, J. Christensen-Dalsgaard, J. D. Do Nascimento, B. Dintrans, H. Kjeldsen, M. J.P.F.G. Monteiro, N. C. Santos, S. Sousa, S. Vauclair

Research output: Contribution to journalArticlepeer-review


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.

Original languageEnglish (US)
Article numberA106
JournalAstronomy and Astrophysics
StatePublished - 2012


  • Methods: data analysis
  • Stars: individual: 18 Sco
  • Stars: oscillations
  • Techniques: radial velocities

ASJC Scopus subject areas

  • Astronomy and Astrophysics
  • Space and Planetary Science


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