The radius and mass of the subgiant star bet Hyi from interferometry and asteroseismology

Authors :: North, J. R.
Davis, J.
Bedding, T. R.
Ireland, M. J.
Jacob, A. P.
O'Byrne, J.
Owens, S. M.
Robertson, J. G.
Tango, W. J.
Tuthill, P. G.
Publication Year :: 2007
Abstract: We have used the Sydney University Stellar Interferometer (SUSI) to measure the angular diameter of beta Hydri. This star is a nearby G2 subgiant whose mean density was recently measured with high precision using asteroseismology. We determine the radius and effective temperature of the star to be 1.814+/-0.017 R_sun (0.9%) and 5872+/-44 K (0.7%) respectively. By combining this value with the mean density, as estimated from asteroseismology, we make a direct estimate of the stellar mass. We find a value of 1.07+/-0.03 M_sun (2.8%), which agrees with published estimates based on fitting in the H-R diagram, but has much higher precision. These results place valuable constraints on theoretical models of beta Hyi and its oscillation frequencies.<br />Comment: 3 figures, 3 tables, to appear in MNRAS Letters

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