RESEARCH
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The radius and mass of the close solar twin 18 Scorpii derived from asteroseismology and interferometry

M. Bazot, M. J. Ireland, D. Huber, T. R. Bedding, A.-M. Broomhall, T. L. Campante, H. Carfantan, W. J. Chaplin, Y. Elsworth, J. MelÚndez, P. Petit, S. ThÚado, V. Van Grootel, T. Arentoft, M. Asplund, M. Castro, J. Christensen-Dalsgaard, J. D. do Nascimento Jr., B. Dintrans, X. Dumusque, H. Kjeldsen, H. McAlister, T. S. Metcalfe, M. J. P. F. G. Monteiro, N. C. Santos, S. G. Sousa, J. Sturmann, L. Sturmann, T. A. ten Brummelaar, N. Turner, S. Vauclair

Abstract
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 R were estimated. We used these values to derive the mass of the star, 1.02 ± 0.03 M.

Keywords
stars: individual: 18 Sco - stars: oscillations - techniques: radial velocities - techniques: interferometric - methods: data analysis

Notes
Based on observations collected at the European Southern Observatory (ID 183.D-0729(A)) and at the CHARA Array, operated by Georgia State University.

Astronomy and Astrophysics
Volume 526, Number of pages L4_1
2011 February

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Instituto de Astrof├şsica e Ci├¬ncias do Espa├žo Universidade do Porto Faculdade de Ciências da Universidade de Lisboa Funda├ž├úo para a Ci├¬ncia e a Tecnologia
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